Image display unit

ABSTRACT

It is configured such that one lens surface of the convex lenses (L 21 , L 22 ) which are located near to pupil H of the eyeball and with respect to which the deflection angles of the light beams are larger is made a conic surface having a conic constant K&lt;0 and, at the same time, such that, to correct the chromatic aberration, a cemented lens (L 23 , L 24 ) made by combining glass materials which are different from each other is provided. The cemented lens is constituted by at least two lenses; the cemented portion of the cemented lens is made a concave surface on the pupil side; the color dispersion of the pupil side lens of the cemented lens is smaller than that of the other lens; and the cemented lens has a convex-concave-convex form, which form has a high chromatic aberration correcting effect. By this, an image display device that can provide sufficiently good images even relative to the shift of the crystalline lens from the eyepiece center that occurs when the eyeball moves and even in the condition of the associated chromatic aberration is realized.

TECHNICAL FIELD

The present invention relates to an image display device that is usedwith it being positioned near to the eyeballs.

BACKGROUND ART

There are many kinds of image display devices, e.g., a television, apersonal computer, a projector, a video camera, and a cell phone;however, such conventional image display devices are limited in theirdisplay size, and thus such a wide range of image as is actually viewedby human eyes has not been able to be obtained from such displays.

On the other hand, as portable displays, an eyeglass type display and ahead mount type display, both called a wearable display, are known. As awearable display, there is known a method in which, as shown in FIG.28(a), small half mirror 40 is arranged at a portion of the field ofview, and an image outputted from image output device 39 such as aplasma display or a liquid crystal is, via projection optical system 38,deflected by half mirror 40 and is projected onto the retina of theeyeball. This method uses the half mirror and thus is such a system (thefirst type) as the image outputted from image output device 39 is viewedas floating in a portion of the field of view. However, as the field ofview angle, a few degrees can only be obtained. As the application ofthis type wearable display, presentation of the image information of acell phone has been conceived, for example.

On the other hand, as a method to obtain a little larger imageinformation, there is a system as shown in FIG. 28(b). In this method, alarge optical element 41 is arranged before the eyeball, and the imageoutputted from image output device 39 is, via a plurality of reflectingsurfaces and projection optical system 42, projected onto the retina ofthe eyeball. While with respect to this type of method, a relativelylarge field of view angle (about 15 to 22.5 degrees) can be obtained,only the type in which the field of view is completely obstructed hasbeen proposed. Thus, as the applicable method thereof, there have beenproposed a system (the second type) in which this type image displaydevice is detachably disposed before one eye and is used as a display asa wearable personal computer, and a system (the third type) in which thesame image display devices are each independently positioned before eachof the eyes and are used instead of a television or a projector.

The above-described three types of the prior art image display deviceswere respectively expected to substitute, as a wearable display, thecell phone, the notebook computer, and the television or the projector.However, as a matter of fact, while they have the advantage ofwearableness, they do not differ much from the conventional displaydevices with respect to the size of the display field of view, and whenconsidering the bother of wearing them, the eyestrain with the field ofview being obstructed, and the weight to be supported by the ears or thehead, they have the disadvantage that they are featured in conspicuousdefects. Furthermore, even in the case of the display devices having alarge field of view angle, the field of view angle is in the range ofabout ±15 to ±22.5 degrees, and thus a sense of realism could beobtained.

On the other hand, as systems describing the method to obtain a largefield of view by allowing the weight to increase and by using aplurality of lenses as the eyepiece, there are, for example, suchsystems as described in Japanese Unexamined Patent Publication No.7-244246 or Japanese Unexamined Patent Publication No. 2001-311910, andin such systems, a field of view angle of ±22.5 degrees or more can berealized. However, such systems have a wide field of view angle only inthe condition that the eyeball does not move, and neither the shift ofthe crystalline lens from the eyepiece center that occurs when theeyeball moves nor the associated chromatic aberration is sufficientlytaken account of.

In addition, with respect to these kinds of devices having a large fieldof view angle, because the eyepiece optical system becomes large-sized,resulting in the weight increase, and thus there arises the disadvantagethat such devices no longer meet the weight requirements of the HMD typedisplay supported by the head or of the eyeglass type display of whichweight is supported by the nose and the ears like eyeglasses.

DISCLOSURE OF THE INVENTION

The present invention has been made in consideration of such situations,and its object is to provide an image display device that has a largefield of view angle comparable to the field of view actually viewed by ahuman and can further provide a sufficiently good image even relative tothe shift of the crystalline lens from the eyepiece center that occurswhen the eyeball moves and even in the condition of the associatedchromatic aberration.

A first invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, the lightemitted from a first two-dimensionally light emitting type photoelectricdevice which is perpendicular to the light beam emitting direction ontofirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that the center distance between said first and secondlight diffusing bodies is within 5.5 to 7.5 cm, in that said first andsecond eyepiece optical systems are each constituted by at least twolenses composed of, sequentially from the eyeball's crystalline lensside, one or more convex lens(es) and a cemented lens, in that at leastone surface of the lens surfaces of said convex lens(es) is a conicsurface with conic constant K<0, in that the cemented portion of saidcemented lens is made a convex surface on the side of said lightdiffusing body, and in that the color dispersion of the light diffusingbody side lens of said cemented lens is made larger than that of theother lens thereof.

As will be described later in detail in the best mode for carrying outthe invention section, the center distance between the first and secondlight diffusing bodies is required to be within 5.5 to 7.5 cm so thatthe image is transmitted to the right and left eyes and the positions ofthe optical systems for the right and left eyes do not interfere witheach other. In order to successfully project and image, under thiscondition, the images onto the retina in the eyeball, with the imagedimages being a wide range image having a field of view angle of ±22.5degrees or more, which performance has been impossible in the past, itis necessary to dispose a convex lens at a position which is as near aspossible to the crystalline lens and to make the respective principallight rays of different light beams from relatively near regions enterthe crystalline lens, with each principal light ray being given a largeangle change by the effect of the convex lens. Thus, in this invention,it is configured such that one or more convex lens(es) is (are) disposedat a position near to the crystalline lens and that no concave lens isprovided in this portion.

Further, in this case, in order to obtain a good image even when thelateral shift of the pupil (hereinafter, also referred to as“look-around eye” or “look-around eye action”) occurs, it is necessaryto improve the astigmatism occurring around the convex lens(es). Forthis purpose, at least one surface of the lens surfaces of the convexlens(es) is made a conic surface with conic constant K<0. In addition,in order to improve the chromatic aberration occurring in thisconfiguration, a cemented lens is provided on the light diffusing bodyside of the convex lens(es).

In particular, because, with respect to the first and second eyepieceoptical systems, it is configured such that by positioning the asphericconvex lens(es) on the eyeball side, the respective principal light raysenter the pupil of the eyeball, with each of the principal light raysbeing given a large angle, the inclination of the principal light ray ofeach light beam at the light diffusing body is relatively small. Thus,with the cemented lens being used at a position near to the lightdiffusing body, the incident angles at the cemented surface are not verylarge, which makes it possible to correct the chromatic aberration well.

To improve chromatic aberration by means of a cemented lens, thecemented surface is required to be convex toward the lens having alarger color dispersion; and thus, in this invention, the cementedportion of the cemented lens is made a convex surface on the side of thelight diffusing body, and the color dispersion of the light diffusingbody side lens of the cemented lens is made larger than that of theother lens thereof.

By this, the field of view angle can be made larger without making thesize of the optical system larger, and the optical system can be made anoptical system of which various aberrations, including astigmatism andchromatic aberration, are small. In addition, in order to make the imageobservable when the field of view angle is enlarged with the lightincident on the cemented lens being made non-telecentric, it isconfigured such that the light from the first photoelectric device isfirst imaged on the light diffusing body, and the diffused light fromthe intermediate image enters the eyeball.

A second invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, the lightemitted from a first two-dimensionally light emitting type photoelectricdevice which is perpendicular to the light beam emitting direction ontofirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that the center distance between said first and secondlight diffusing bodies is within 5.5 to 7.5 cm, in that said first andsecond eyepiece optical systems are each constituted by at least twolenses composed of, sequentially from the eyeball's crystalline lensside, one or more convex lens(es) and a cemented lens, in that at leastone surface of the lens surfaces of said convex lens(es) is a conicsurface with conic constant K<0, in that the cemented portion of saidcemented lens is made a concave surface on the side of said lightdiffusing body, and in that the color dispersion of the light diffusingbody side lens of said cemented lens is made smaller than that of theother lens thereof.

This invention differs from the above-described first invention only inthat the cemented portion of the cemented lens is made a concave surfaceon the side of the light diffusing body, and accordingly the colordispersion of the light diffusing body side lens of said cemented lensis made smaller than that of the other lens thereof; and thus theoperation/working-effect of this invention is the same as that of thefirst invention.

A third invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, the lightemitted from a first two-dimensionally light emitting type photoelectricdevice which is perpendicular to the light beam emitting direction ontofirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that the center distance between said first and secondlight diffusing bodies is within 5.5 to 7.5 cm, in that said first andsecond eyepiece optical systems are each constituted by at least twolenses composed of, sequentially from the eyeball's crystalline lensside, one or more convex lens(es) and a cemented lens, in that at leastone surface of the lens surfaces of said convex lens(es) is a conicsurface with conic constant K<0, in that said cemented lens has at leasttwo cemented portions, in that the cemented surface located near to saidlight diffusing body is made a concave surface on the side of said lightdiffusing body, in that the other cemented surface is made a convexsurface on the side of said light diffusing body, and in that the colordispersion of the center lens bounded by said cemented portions is madelarger than those of the other two lenses surrounding the center lens.

This invention differs from the above-described first and secondinventions only in that the cemented lens has at least two cementedportions to further improve the chromatic aberration, and theoperation/working-effect of this invention does not differ basicallyfrom those of the first and second inventions. In this regard, it isconfigured such that with the color dispersion of the center lensbounded by the cemented portions being made larger than those of theother two lenses surrounding the center lens, the cemented portions areeach made a convex surface toward the center lens, i.e., the center lensis made a concave lens. Generally, the cemented lens may be constitutedby three lenses only; however, when four or more lenses are used, thecombination of the lenses other than the both end lenses should only bea lens system equivalent to the one center lens above-described.

A fourth invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, the lightemitted from a first two-dimensionally light emitting type photoelectricdevice which is perpendicular to the light beam emitting direction ontofirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that the center distance between said first and secondlight diffusing bodies is within 5.5 to 7.5 cm, in that said first andsecond eyepiece optical systems are each constituted by at least twolenses composed of, sequentially from the eyeball's crystalline lensside, one or more convex lens(es) and a cemented lens, in that at leastone surface of the lens surfaces of said convex lens(es) is a conicsurface with conic constant K<0, in that said cemented lens has at leasttwo cemented portions, in that the cemented surface located near to saidlight diffusing body is made a convex surface on the side of said lightdiffusing body, in that the other cemented surface is made a concavesurface on the side of said light diffusing body, and in that the colordispersion of the center lens bounded by said cemented portions is madesmaller than those of the other two lenses surrounding the center lens.

This invention differs from the third invention only in that it isconfigured such that with the color dispersion of the center lensbounded by the cemented portions being made larger than those of theother two lenses surrounding the center lens, the cemented portions areeach made a concave surface toward the center lens, i.e., the centerlens is made a convex lens, and thus the operation/working-effect ofthis invention is the same as that of the above-described thirdinvention.

A fifth invention to achieve the above-described object is any one ofthe above-described first to fourth inventions, characterized in that atleast one surface of the lens surfaces of said convex lens(es) is aconic surface with conic constant K<−1.

In this invention, because at least one surface of the lens surfaces ofthe convex lens(es) is made a conic surface with conic constant K<−1,the aberrations at the lens periphery can be further improved.Accordingly, the curvatures of the convex lens(es) can be made larger;and thus, a lens material with a small refractive index and a smallcolor dispersion can be applied to the convex lens(es). This facilitatesthe design of the cemented lens for achromatization.

A sixth invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, the lightemitted from a first two-dimensionally light emitting type photoelectricdevice which is perpendicular to the light beam emitting direction ontofirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that the center distance between said first and secondlight diffusing bodies is within 5.5 to 7.5 cm, in that said first andsecond eyepiece optical systems are each constituted by at least twolenses composed of, sequentially from the eyeball's crystalline lensside, one or more convex lens(es) and a cemented lens, in that thecemented portion of said cemented lens is made a convex surface on theside of said light diffusing body, in that the color dispersion of thelight diffusing body side lens of said cemented lens is made larger thanthat of the other lens thereof, and in that said light diffusing body ismade a curved surface having a concave surface shape toward saidcemented lens.

The most important characteristic of this invention is that the lightdiffusing body is made a curved surface having a concave surface shapewhen viewed from the cemented lens direction. By making the lightdiffusing body such a curved surface, the size of the light diffusingbody can be evaded from being made large even when the light beamsproceeding from the light diffusing body to the cemented lens are of aconverging direction type. Thus, the light beams that are of aconverging direction type when proceeding from the light diffusing bodyto the cemented lens can be used, and with this converging amount beingtaken advantage of, the image magnification of the convex lens(es) canbe made smaller. By this, the occurrence of the distortion andaberrations can be lessened; in addition, because a lens material with asmall refractive index and a small color dispersion can be applied tothe convex lens(es), the achromatization design is also facilitated.

A seventh invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, the lightemitted from a first two-dimensionally light emitting type photoelectricdevice which is perpendicular to the light beam emitting direction ontofirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that the center distance between said first and secondlight diffusing bodies is within 5.5 to 7.5 cm, in that said first andsecond eyepiece optical systems are each constituted by at least twolenses composed of, sequentially from the eyeball's crystalline lensside, one or more convex lens(es) and a cemented lens, in that thecemented portion of said cemented lens is made a concave surface on theside of said light diffusing body, in that the color dispersion of thelight diffusing body side lens of said cemented lens is made smallerthan that of the other lens thereof, and in that said light diffusingbody is made a curved surface having a concave surface shape toward saidcemented lens.

This invention differs from the above-described sixth invention only inrespect to the configuration of the cemented lens and has the sameoperation/working-effect as the sixth invention.

An eighth invention to achieve the above-described object is theabove-described sixth or seventh invention, characterized in that atleast one surface of the lens surfaces of said convex lens(es) is aconic surface with conic constant K<0.

In this invention, because at least one surface of the lens surfaces ofthe convex lens(es) is made a conic surface with conic constant K<0, theastigmatism occurring around the convex lens(es) can be improved.

A ninth invention to achieve the above-described object is theabove-described eight invention, characterized in that at least onesurface of the lens surfaces of said convex lens(es) is a conic surfacewith conic constant K<−1.

In this invention, because at least one surface of the lens surfaces ofthe convex lens(es) is made a conic surface with conic constant K<−1,the astigmatism occurring around the convex lens(es) can be furtherimproved.

A tenth invention to achieve the above-described object is any one ofthe above-described first to ninth inventions, characterized in that thedistance between the optical centers of said first and second eyepieceoptical systems and the distance between the centers of the projectedimages on said first and second light diffusing bodies are madeadjustable so that those two distances are equal to the eye-width.

In this invention, the distance between the optical centers of the firstand second eyepiece optical systems and the distance between the centersof the projected images on the first and second light diffusing bodiesare made adjustable; and thus, by adjusting the distances in accordancewith the user's eye-width, the optical centers of the first and secondeyepiece optical systems and the centers of the projected images on thefirst and second light diffusing bodies can always be positioned at thecenters of the user's eyes. Note that the term “eye-width” as used inthe present specification and claims means the distance between botheyes.

An eleventh invention to achieve the above-described object is any oneof the above-described first to tenth inventions, characterized in thatsaid relay optical system makes the projection magnification of theimage of said first photoelectric device projected onto said lightdiffusing bodies variable, in that said relay optical system is anon-telecentric system in which the principal ray of each light beamincident on said light diffusing bodies changes from of a divergingdirection type to of a converging direction type when the projectionmagnification changes from a magnifying magnification to a reducingmagnification, and in that the principal rays that are emitted from saidlight diffusing bodies and reach the pupil of said eyeball are inclinedtoward the converging direction when the principal rays are emitted fromsaid light diffusing bodies.

In this invention, because the relay optical system can make theprojection magnification of the light beams to be projected onto thelight diffusing bodies variable, the image of the first photoelectricdevice can be projected onto the user's eyes, with the magnification ofthe image being varied. In this regard, while depending on theprojection magnification of the relay optical system, the principal rayof each light beam proceeding to the light diffusing bodiesnon-telecentrically changes from of a diverging direction type to of aconverging direction type, the principal rays that are emitted from saidlight diffusing bodies and reach the pupil of said eyeball can be made,through the effect of the light diffusing bodies, inclined toward theconverging direction when the principal rays are emitted from said lightdiffusing bodies. Thus, the eyepiece optical systems can be designedwithout being constrained by the principal rays of the relay opticalsystem.

A twelfth invention to achieve the above-described object is any one ofthe above-described first to eleventh inventions, characterized in thatsaid light diffusing bodies that diffuse light are a transmission typediffusing plate constituted by a transmission plate on which abrasivegrains of a metal oxide or metallic carbide of which grain diameter isprecisely controlled with micron-grade are coated.

By the use of such a diffusing plate, the diffusing angle can be made±60 degrees or more, and even in the case of taking the look-around eyeinto account, a field of view angle of ±22.5 degrees or more can besecured. Further, even when observing an image quality comparable tothat of a DVD or high-definition image, the diffusing plate coated withsuch abrasive grains does not make one feel a sense of abrasive grainsand makes it possible to obtain a natural image quality.

A thirteenth invention to achieve the above-described object is theabove-described twelfth invention, characterized in that said abrasivegrains are made of at least one of silicon carbide, chromium oxide, tinoxide, titanium oxide, magnesium oxide, and aluminum oxide and in thatsaid transmission plate is a polyester film.

The abrasive grains made of such materials are adequate to be mademicron-grade grains, and because the polyester film is tough, a highdurability can be obtained.

A fourteenth invention to achieve the above-described object is any oneof the above-described first to thirteenth inventions, characterized inthat it has a second two-dimensionally light emitting type photoelectricdevice that is arranged such that the light beams thereof areperpendicular to those of said first photoelectric device and also has,in said relay optical system, which projects the light emitted from saidfirst photoelectric device onto said light diffusing bodies, a lightdivider that divides the light beams and leads them to said first andsecond light diffusing bodies, in that the light beams from said secondphotoelectric device are made incident on said light divider such thatthe light beams are perpendicular to the light beams emitted from saidfirst photoelectric device, and in that said light divider has afunction to divide the light from said first photoelectric device fromthe light from said second photoelectric device and also to combine thedivided light beams of said first photoelectric device with the dividedlight beams of said second photoelectric device and lead them to saidfirst light diffusing body and to said second light diffusing body,respectively.

In this invention, the light divider divides the light beams of thelight emitted from the first photoelectric device and leads them to thefirst (right eye use) and second (left eye use) light diffusing bodiesand also receives the light from the second photoelectric device,divides it, and further combines it with the light beams of the firstphotoelectric device to lead them to the first and second lightdiffusing bodies. Thus, the combined image of the image of the firstphotoelectric device and the image of the second photoelectric device isprojected onto the light diffusing bodies for right and left eyes and isprojected by the eyepiece optical systems onto the retinas of the rightand left eyes.

A fifteenth invention to achieve the above-described object is theabove-described fourteenth invention, characterized in that thedifference between the number of reflections by mirrors experienced bythe light beams emitted from said first photoelectric device from thefirst reflection by a mirror up to reaching the user's eyes and thenumber of reflections by mirrors experienced by the light beams emittedfrom said second photoelectric device from the first reflection by amirror up to reaching the user's eyes is 0 or an even number.

In this invention, by adopting such configuration, the right and leftstates of the light beams emitted from the first photoelectric deviceand the second photoelectric device are projected to the user's eyes inthe same condition.

A sixteenth invention to achieve the above-described object is theabove-described fourteenth or fifteenth invention, characterized in thatthe difference between the number of reflections by mirrors experiencedby the light beams emitted from said first photoelectric device from thefirst reflection by a mirror up to reaching the user's right eye and thenumber of reflections by mirrors experienced by the light beams emittedfrom said first photoelectric device from the first reflection by amirror up to reaching the user's left eye is 0 or an even number and inthat the difference between the number of reflections by mirrorsexperienced by the light beams emitted from said second photoelectricdevice from the first reflection by a mirror up to reaching the user'sright eye and the number of reflections by mirrors experienced by thelight beams emitted from said second photoelectric device from the firstreflection by a mirror up to reaching the user's left eye is 0 or aneven number.

By adopting such configuration, both of the image of the firstphotoelectric device and the image of the second photoelectric deviceare projected to the user's eyes, without the right and left state beingreversed relative to the right and left eyes.

A seventeenth invention to achieve the above-described object is any oneof the above-described fourteenth to sixteenth inventions, characterizedin that the distance between the optical centers of said first andsecond eyepiece optical systems and the distance between the centers ofthe projected images on said first and second light diffusing bodies aremade adjustable so that those two distances are equal to the eye-widthand in that an optical path length adjusting mechanism that adjust, whenthe two distances, the distance between the optical centers of theeyepiece optical systems and the distance between the centers of theprojected images, are adjusted, the optical path length from said firstphotoelectric device to the user's eyes and the optical path length fromsaid second photoelectric device to the user's eyes so that each of themdoes not change is provided.

In this invention, because even when the two distances, the distancebetween the optical centers of the eyepiece optical systems and thedistance between the centers of the projected images, are adjusted, theoptical path length from said first photoelectric device to the user'seyes and the optical path length from said second photoelectric deviceto the user's eyes can be adjusted so that each of them does not change,the two distances, the distance between the optical centers of theeyepiece optical systems and the distance between the centers of theprojected images can be adjusted, without the image magnification andthe focus position being varied.

An eighteenth invention to achieve the above-described object is any oneof the above-described fourteenth to seventeenth inventions,characterized in that said relay optical system, which projects thelight emitted from said first photoelectric device onto said lightdiffusing bodies, makes the projection magnification relative to saidlight diffusing bodies of the light beams projected onto said lightdiffusing bodies variable and in that an illuminance varying mechanismfor making, when the magnification is varied, the illuminances of therespective pictures projected from said first photoelectric device andsaid second photoelectric device onto said light diffusing bodiessubstantially equal to each other is provided.

In this invention, because the illuminance varying mechanism for making,when the magnification is varied, the illuminances of the respectivepictures projected from said first photoelectric device and said secondphotoelectric device onto said light diffusing bodies substantiallyequal to each other is provided, the illuminances of the picturesobserved can be kept substantially constant, even when the imagemagnification is varied.

A nineteenth invention to achieve the above-described object is any oneof the above-described first to eighteenth inventions, characterized inthat said first photoelectric device is a transmission type orreflection type liquid crystal device element and has three pieces ofliquid crystal devices, each corresponding to each of the colors of G B,and R, and an illumination system that illuminates said liquid crystaldevices and in that said illumination system is a uniformizing opticalsystem that uniformizes the outputs from light emitting LEDs of G, B,and R.

In this invention, because the illumination system is made auniformizing optical system that uniformizes the outputs from lightemitting LEDs of G, B, and R, the liquid crystal device is uniformlyilluminated and thus brightness irregularity does not occur.

A twentieth invention to achieve the above-described object is theabove-described nineteenth invention, characterized in that saiduniformizing optical system has, for each of the LEDs of G, B, and R, aplurality of high intensity LEDs, collects the lights from thoseplurality of LED light emitting portions by using optical fibers, andilluminates said liquid crystal device with the collected lights.

In this invention, because it is configured such that the outputs fromthe plurality of LEDs are collected by use of optical fibers and theliquid crystal device is illuminated with the collected lights, ahigh-illuminance uniform illumination can be obtained.

A twenty-first invention to achieve the above-described object is anyone of the above-described first to eighteenth inventions, characterizedin that said first photoelectric device is a transmission type orreflection type liquid crystal device element and has three pieces ofliquid crystal devices, each corresponding to each of the colors of G,B, and R, and an illumination system that illuminates said liquidcrystal devices and in that said illumination system is cold cathodetubes of G, B, and R.

Cold cathode tubes can be made small-sized with ease, consume a smalleramount of power, and have a long life, and thus are suitable forillumination light for liquid crystal devices.

A twenty-second invention to achieve the above-described object is theabove-described twenty-first invention, characterized in that saiduniformizing optical system has, for each of the colors of G, B, and R,a plurality of cold cathode tubes, collects the lights from thoseplurality of cold cathode tubes by using optical fibers, and illuminatessaid liquid crystal device with the collected lights.

In this invention, because it is configured such that the outputs fromthe plurality of cold cathode tubes are collected by use of opticalfibers and the liquid crystal device is illuminated with the collectedlights, a high-illuminance uniform illumination can be obtained.

A twenty-third invention to achieve the above-described object is anyone of the above-described first to twenty-second inventions,characterized in that at least a portion of said image display device issupported by a portion other than a user, is also in contact with theface of said user, and is made movable in response to the movement ofthe face of said user.

In this invention, because at least a portion of the image displaydevice is supported by a portion other than a user, the user's burdencan be reduced. Further, because the portion is made movable in responseto the movement of the user's face, the image can be observed in acomfortable posture.

A twenty-fourth invention to achieve the above-described object is animage display device which has an optical system that has at least,relative to each of the right and left eyeballs, portions independent ofeach other and which projects an image into each of said right and lefteyeballs, said image display device being characterized in that saidindependent portions are each constituted by at least two lensescomposed of, sequentially from said eyeball side, one or more convexlens(es) and a cemented lens and in that the surface, located distantfrom the eyeball, of the convex lens, among said convex lenses, locatednearest to the eye ball is made a conic surface with conic constant K<0.

In this invention, it is configured such that one or more convexlens(es) is (are) disposed at a position near to the crystalline lensand that no concave lens is provided in this portion.

Further, in this case, in order to obtain a good image even when thelateral shift of the pupil occurs, it is necessary to improve theastigmatism occurring around the convex lens(es). For this purpose, thesurface, located distant from the eyeball, of the convex lens, among theconvex lenses, located nearest to the eye ball is made a conic surfacewith conic constant K<0. In addition, in order to improve the chromaticaberration occurring in this configuration, a cemented lens is providedon the light diffusing body side of the convex lens(es).

More specifically, because it is configured such that by positioning theaspheric convex lens(es) on the eyeball side, the respective principallight rays enter the pupil of the eyeball, with each of the principallight rays being given a large angle, the inclination of the principallight ray of each light beam at the light diffusing body is relativelysmall. Thus, with the cemented lens being used at a position near to thelight diffusing body, the incident angles at the cemented surface arenot very large, which makes it possible to correct the chromaticaberration well.

By this, the field of view angle can be made larger without making thesize of the optical system larger, and the optical system can be made anoptical system of which various aberrations, including astigmatism andchromatic aberration, are small.

A twenty-fifth invention to achieve the above-described object is theabove-described twenty-fourth invention, characterized in that saidcemented lens is provided, in the independent portion of said opticalsystem, on the nearest side of an image forming surface forming saidimage.

In this invention, because the cemented lens is provided, in theindependent portion of the optical system, on the nearest side of theimage forming surface forming said image, chromatic aberration, inparticular, can be efficiently corrected.

A twenty-sixth invention to achieve the above-described object is animage display device characterized in that it has, instead of the firstphotoelectric device of any of the above-described first to thirteenthinventions and nineteenth to twenty-second inventions, twotwo-dimensionally light emitting type photoelectric devices which areperpendicular to the light beam emitting direction and in that it isconfigured such that, instead of projecting, via said relay opticalsystem, the light emitted from said first photoelectric device onto saidfirst and second light diffusing bodies which are independent of eachother relative to the right and left eyes, the lights emitted from saidtwo photoelectric devices are each projected, via said relay opticalsystem, onto said first and second light diffusing bodies which areindependent of each other relative to the right and left eyes.

This invention differs from the above-described first to thirteenthinventions and nineteenth to twenty-second inventions only in that,without using a photoelectric device in common for the right and lefteyes, an independent photoelectric device is used for each of the rightand left eyes, and thus the essential operation/working-effect of thisinvention is the same as that of each of the above-referencedinventions.

A twenty-seventh invention to achieve the above-described object is theabove-described twenty-sixth invention, characterized in that thedistance between the optical centers of said first and second eyepieceoptical systems and the distance between the centers of the projectedimages on said first and second light diffusing bodies are madeadjustable so that those two distances are equal to the eye-width and inthat an optical path length adjusting mechanism that adjust, when thetwo distances, the distance between the optical centers of the eyepieceoptical systems and the distance between the centers of the projectedimages, are adjusted, the optical path lengths from said twophotoelectric device to the user's eyes so that each of them does notchange is provided.

A twenty-eighth invention to achieve the above-described object is theabove-described twenty-sixth or twenty-seventh invention, characterizedin that said relay optical system, which projects the lights emittedfrom said two photoelectric devices onto said light diffusing bodies,makes each of the projection magnifications relative to said lightdiffusing bodies of the light beams projected onto said light diffusingbodies variable and in that an illuminance varying mechanism for making,when the magnifications are varied, the illuminances of the respectivepictures projected from said two photoelectric devices onto said lightdiffusing bodies substantially equal to each other is provided.

In this invention, because the illuminance varying mechanism for keepingthe illuminances, which vary depending on the magnification of the relayoptical system, constant is provided, images with an adequateilluminance can be presented even when the magnification or reduction ofthe images is performed, and thus an image display device that does nottire the user can be realized.

A twenty-ninth invention to achieve the above-described object is animage display device that projects, via a relay optical system, each ofthe lights emitted from two two-dimensionally light emitting typephotoelectric devices which are perpendicular to the light beam emittingdirection onto first and second light diffusing bodies which areindependent of each other relative to the right and left eyes andprojects and images the transmitted images of said light diffusingbodies, via first and second eyepiece optical systems which respectivelycorrespond to the first and second light diffusing bodies, onto theretina in the eyeball, with the imaged transmitted images being a widerange image having a field of view angle of ±22.5 degrees or more, saidimage display device being characterized in that said twotwo-dimensionally light emitting type photoelectric devices are each areflection type liquid crystal device element, in that one light source,a first polarization beam splitter that divides the light emitted fromsaid light source into P-polarized light and S-polarized light, and anoptical system that leads each of the P-polarized light and S-polarizedlight respectively to said two two-dimensionally light emitting typephotoelectric devices, thus illuminates said two two-dimensionally lightemitting type photoelectric devices, and leads the lights reflectedthereby to said relay optical system are provided, and in that saidoptical system leads said P-polarized light and S-polarized light tosaid two-dimensionally light emitting type photoelectric devices via asecond polarization beam splitter and a λ/4 plate and leads the lightsreflected thereby to said relay optical system via said λ/4 plate andsecond polarization beam splitter.

In this invention, reflection type liquid crystal device elements areused as the two-dimensionally light emitting type photoelectric devices.In this regard, one light source is used in common for illuminationthereof; however, if half mirrors or the like are used when illuminatingliquid crystal device elements and leading the lights reflected therebyto other optical paths, about a half amount of light would be lost eachtime.

In this invention, to preclude this, it is configured such that thelight used for the left eye and the light used for the right eye aremade P-polarized light and S-polarized light, respectively, and by usingpolarization beam splitters and a λ/4 plate, the loss of light amount isavoided. A specific method therefor will be described later in theembodiment section.

A thirtieth invention to achieve the above-described object is an imagedisplay device that projects, via a relay optical system, each of thelights emitted from two sets of two-dimensionally light emitting typephotoelectric devices which are perpendicular to the light beam emittingdirection onto first and second light diffusing bodies which areindependent of each other relative to the right and left eyes andprojects and images the transmitted images of said light diffusingbodies, via first and second eyepiece optical systems which respectivelycorrespond to the first and second light diffusing bodies, onto theretina in the eyeball, with the imaged transmitted images being a widerange image having a field of view angle of ±22.5 degrees or more, saidimage display device being characterized in that said two sets oftwo-dimensionally light emitting type photoelectric devices are eachconstituted by three reflection type liquid crystal device elements,each corresponding to each of the colors of G, B, and R, in that onelight source, a first polarization beam splitter that divides the lightemitted from said light source into P-polarized light and S-polarizedlight, and an optical system that leads each of the P-polarized lightand S-polarized light respectively to said two sets of two-dimensionallylight emitting type photoelectric devices, thus illuminates said twotwo-dimensionally light emitting type photoelectric devices, and leadsthe lights reflected thereby to said relay optical system are provided,and in that said optical system leads said P-polarized light andS-polarized light to said two-dimensionally light emitting typephotoelectric devices, which accommodate the colors of G, B, and R, viaa second polarization beam splitter, a λ/4 plate, and an RGB light beamdivision multiplexer prism and leads the lights reflected thereby tosaid relay optical system via said RGB light beam dividing/multiplexingprism, said λ/4 plate, and said second polarization beam splitter.

In this invention, the light from the light source is divided by the RGBlight beam division multiplexer prism into each of the colors of G, B,and R, and the reflection type liquid crystal device elements are eachilluminated with each light. Each lights reflected by each reflectiontype liquid crystal device element are made one light beam by the RGBlight beam division multiplexer prism. Thus, different reflected lightsfrom different patterns, each of which correspond to each of the colorsof G, B, and R, can be obtained.

A thirty-first invention to achieve the above-described object is theabove-described twenty-ninth or thirtieth invention, wherein said lightsource is a plurality of white light LEDs two-dimensionally arranged inan array form.

White light LEDs have a larger brightness and a higherelectricity-to-light conversion efficiency compared with other types oflight sources and thus feature low heat generation and low powerconsumption, which makes such LEDs excel as the light source.

A thirty-second invention to achieve the above-described object is theabove-described twenty-ninth or thirtieth invention, characterized inthat said light source has a group of R color LEDs, a group of G colorLEDs, and a group of B color LEDs, each being constituted by a pluralityof the respective color LEDs two-dimensionally arranged in an arrayform, and an RGB light beam division multiplexer prism that combines thelights emitted by those groups.

White light LEDs have a simple optical system and excel in space saving;however, because their color wavelength condition and light intensitydepend on their specifications, there are many problems in finelyadjusting their color condition. In the invention, to address suchsituation, it is configured such that the LEDs are divided into threegroups, the group of R color LEDs, the group of G color LEDs, and thegroup of B color LEDs, and each light beams are combined by the RGBlight beam multiplexer prism. This enables the adjustment of the colorof the light source.

A thirty-third invention to achieve the above-described object is anyone of the above-described twenty-ninth to thirty-second inventions,characterized in that the optical system, which leads the light emittedfrom said light source to said two-dimensionally light emitting typephotoelectric devices, has an illumination uniformizing optical system.

Especially when LEDs are two-dimensionally arranged, illuminationirregularity may occur. In this invention, because the optical system,which leads the light emitted from the light source to thetwo-dimensionally light emitting type photoelectric devices, has anillumination uniformizing optical system, the illumination irregularitycan be alleviated.

A thirty-fourth invention to achieve the above-described object is theabove-described thirty-third invention, characterized in that saidillumination uniformizing optical system is at least one rod and in thatthe final exit plane of said rod and the surface of saidtwo-dimensionally light emitting type photoelectric devices are madesubstantially conjugate with each other.

A rod is a cylinder of which inner surface is mirror finished. Lightthat passes through a rod is uniformized, with the light experiencingmultiple reflections at the rod's inner surface, and the rod's finalexit plane can be regarded as a uniform secondary light source. Withthis plane and the surface of the two-dimensionally light emitting typephotoelectric devices are made substantially conjugate with each other,the two-dimensionally light emitting type photoelectric devices can beuniformly illuminated. “Substantially conjugate” means that deviationfrom the exact conjugate position is allowed so long as a requireduniform illumination degree can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a drawing showing an outline of an eyepiece optical systemfrom which the embodiments of the present invention start.

FIG. 1B is a drawing showing the aberration of the eyepiece opticalsystem shown in FIG. 1A.

FIG. 1C is a lateral aberration plot output drawing of the eyepieceoptical system shown in FIG. 1A.

FIG. 2A is a drawing showing an outline of an eyepiece optical systemused in an embodiment of the present invention.

FIG. 2B is a drawing showing the aberration of the eyepiece opticalsystem shown in FIG. 2A.

FIG. 2C is a lateral aberration plot output drawing of the eyepieceoptical system shown in FIG. 2A.

FIG. 2D is a ray tracing drawing of the eyepiece optical system shown inFIG. 2A in the case of 30-degree look-around eye.

FIG. 2E is a plot output drawing showing the lateral aberration of 30±10degrees of the eyepiece optical system shown in FIG. 2A.

FIG. 3 is a drawing showing the shift of the field of view centerassociated with a human look-around eye action.

FIG. 4A is a drawing showing an outline of an eyepiece optical systemused in an embodiment of the present invention.

FIG. 4B is a drawing showing the aberration of the eyepiece opticalsystem shown in FIG. 4A.

FIG. 4C is a ray tracing drawing of the eyepiece optical system shown inFIG. 4A in the case of 30-degree look-around eye.

FIG. 4D is a plot output drawing showing the lateral aberration of 30±10degrees of the eyepiece optical system shown in FIG. 4A.

FIG. 5A is a drawing showing an outline of an eyepiece optical systemused in an embodiment of the present invention.

FIG. 5B is a ray tracing drawing of the eyepiece optical system shown inFIG. 5A in the case of 30-degree look-around eye.

FIG. 5C is a plot output drawing showing the lateral aberration of 30±10degrees of the eyepiece optical system shown in FIG. 5A.

FIG. 6A is a drawing showing an outline of an eyepiece optical systemused in an embodiment of the present invention.

FIG. 6B is a drawing showing the aberration of the eyepiece opticalsystem shown in FIG. 6A.

FIG. 6C is a ray tracing drawing of the eyepiece optical system shown inFIG. 6A in the case of 30-degree look-around eye.

FIG. 6D is a plot output drawing showing the lateral aberration of 30±10degrees of the eyepiece optical system shown in FIG. 6A.

FIG. 7A is a drawing showing an outline of an eyepiece optical systemused in an embodiment of the present invention.

FIG. 7B is a drawing showing the aberration of the eyepiece opticalsystem shown in FIG. 7A.

FIG. 7C is a ray tracing drawing of the eyepiece optical system shown inFIG. 7A in the case of 30-degree look-around eye.

FIG. 7D is a plot output drawing showing the lateral aberration of 30±10degrees of the eyepiece optical system shown in FIG. 7A.

FIG. 7E is a drawing comparing the MTF (b) at the best focus position ofthe combination of the conic surface and the chromatic aberrationcorrecting lens of the optical system shown in FIG. 7A where there is afield of view center with the MTF (a) at the best focus position of aconventional optical system.

FIG. 7F is a drawing showing an outline of a modification example of theeyepiece optical system shown in FIG. 7A.

FIG. 8A is a drawing showing an outline of an eyepiece optical systemused in an embodiment of the present invention.

FIG. 8B is a drawing showing the aberration of the eyepiece opticalsystem shown in FIG. 8A.

FIG. 8C is a ray tracing drawing of the eyepiece optical system shown inFIG. 8A in the case of 30-degree look-around eye.

FIG. 8D is a plot output drawing showing the lateral aberration of 30±10degrees of the eyepiece optical system shown in FIG. 8A.

FIG. 8E is a drawing showing a liquid crystal device illumination of anembodiment of the present invention, using high intensity LEDs andfibers.

FIG. 8F is a drawing showing a liquid crystal device illumination of anembodiment of the present invention, using cold cathode tubes andfibers.

FIG. 9A is an optical path drawing where a zoom optical system used inan embodiment of the present invention has a field angle of 12.4 mm.

FIG. 9B is a field aberration output drawing in the state of FIG. 9A.

FIG. 9C is a spot diagram output drawing in the state of FIG. 9A.

FIG. 9D is a lateral aberration plot output drawing in the state of FIG.9A.

FIG. 10A is an optical path drawing where the zoom optical system shownin FIG. 9A has a field angle of 25.13 mm.

FIG. 10B is a field aberration output drawing in the state of FIG. 10A.

FIG. 10C is a spot diagram output drawing in the state of FIG. 10A.

FIG. 10D is a lateral aberration plot output drawing in the state ofFIG. 10A.

FIG. 11A is an optical path drawing where the zoom optical system shownin FIG. 9A has a field angle of 63.6 mm.

FIG. 11B is a field aberration output drawing in the state of FIG. 11A.

FIG. 11C is a spot diagram output drawing in the state of FIG. 11A.

FIG. 11D is a lateral aberration plot output drawing in the state ofFIG. 11A.

FIG. 12A is an optical path drawing when the field angle of a zoomoptical system used in an embodiment of the present invention is varied.(a) corresponds to a field angle of 18.5 mm; (b) corresponds to a fieldangle of 31.92 mm; (c) corresponds to a field angle of 63.13 mm.

FIG. 12B is a spot diagram output drawing regarding the zoom opticalsystem shown in FIG. 12A.

FIG. 12C is a drawing showing the MTF in the state of (a) of FIG. 12A.

FIG. 12D is a drawing showing the MTF in the state of (b) of FIG. 12A.

FIG. 12E is a drawing showing the MTF in the state of (c) of FIG. 12A.

FIG. 12F is a drawing showing the table of each state when the zoomcondition of the zoom optical system shown in FIG. 12A is varied.

FIG. 12G is a drawing showing each MTF of the zoom optical system shownin FIG. 12A at each frequency starting from an evaluation frequency,when the zoom optical system has a field of view angle of 18.50 degrees.

FIG. 12H is a drawing showing each MTF of the zoom optical system shownin FIG. 12A at each frequency starting from an evaluation frequency,when the zoom optical system has a field of view angle of 31.92 degrees.

FIG. 13A is a drawing showing an example in which the zoom opticalsystem shown in FIG. 12A is arranged for one eye use.

FIG. 13B is a drawing showing an example in which the zoom opticalsystem shown in FIG. 12A is arranged for the other eye use.

FIG. 13C is a drawing showing the arrangement in which the zoom systemshown in FIG. 13A and the zoom optical system shown in FIG. 13B arecombined to be used for both eyes use.

FIG. 13D is a drawing showing the entire arrangement in which eyepieceoptical systems are combined with the zoom system shown in FIG. 13C.

FIG. 13E is a drawing showing an example of an optical system foradjusting the optical system to the eye-width, without the opticallength being changed.

FIG. 14 is an optical path side view showing an example in which thezoom optical system shown in FIG. 9A is arranged in a folding manner sothat the zoom optical system is accommodated in a compact manner.

FIG. 15 is an outline drawing showing a holding mechanism for thedisplay portion, an embodiment of the present invention.

FIG. 16 is a drawing showing an example of the arrangement of theoptical path parts where the optical system shown in FIG. 14 isaccommodated in a case to be mounted on the face.

FIG. 17A is a drawing showing an example of optical elements of an imagedisplay device, another embodiment of the present invention.

FIG. 17B is an outline drawing showing the state, as viewed from theside, in which the image display device shown in FIG. 17A is mounted onthe head.

FIG. 18 is a drawing showing a part of an optical system, an embodimentof the present invention.

FIG. 19 is a drawing showing a modification example of the opticalsystem shown in FIG. 18.

FIG. 20 is a drawing showing an example of an optical system formedbehind the optical system shown in FIG. 18 or FIG. 19.

FIG. 21 is a drawing showing an example of an optical system forprojecting a combined image from two two-dimensionally light emittingtype photoelectric devices (reflection type liquid crystal devices) tothe right and left eyes.

FIG. 22 is a drawing showing an outline of an optical system forprojecting images from two-dimensionally light emitting typephotoelectric devices (reflection type liquid crystal devices), eachprovided for each of the right and left eyes, to the right and lefteyes.

FIG. 23 is a schematic diagram showing the state in which an imagedisplay device, an embodiment of the present invention, is used in asitting posture.

FIG. 24 is a schematic diagram showing the state in which an imagedisplay device, an embodiment of the present invention, is used in alying posture.

FIG. 25 is a schematic showing an example of a system for leading outputimages from two two-dimensional image output devices to both eyes.

FIG. 26A is a drawing showing an example of a configuration of aconventional eyepiece lens system.

FIG. 26B is a field aberration output drawing of the eyepiece opticalsystem shown in FIG. 26A.

FIG. 26C is a lateral aberration plot output drawing at ±15 degrees ofthe eyepiece optical system shown in FIG. 26A.

FIG. 26D is a lateral aberration plot output drawing at ±30 degrees ofthe eyepiece optical system shown in FIG. 26A.

FIG. 27A is a drawing showing an example of a configuration of aconventional eyepiece lens system.

FIG. 27B is a field aberration output drawing of the eyepiece opticalsystem shown in FIG. 27A.

FIG. 27C is a lateral aberration plot output drawing at ±15 degrees ofthe eyepiece optical system shown in FIG. 27A.

FIG. 28 is a drawing showing representative embodiments of eyeglass typedisplay and head mount type display.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, examples of the mode for carrying out the presentinvention will be described, referring to the drawings. First, to fosterbetter understanding, the reason why it is difficult to realize anoptical system having a field of view angle of ±22.5 degrees or morewill be explained briefly. FIGS. 26A-26D show an example of an opticalsystem designed to obtain a large field of view angle. This is, as shownin the optical system schematic of FIG. 26A, an example of the case inwhich assuming the human pupil as H relative to light emitting pictureplane G (which, although called light emitting picture plane here,includes not only an object that emits light by itself or forms an imageby reflecting light, but also an object, such as a screen, in which animage is projected thereon and the light coming out therefrom isobserved by the eye), three convex lenses L1, L2, and L3 that are madeof glass material LAC7 having a low refractive index but having a smallcolor dispersion and have a curvature of 220 cm are used, and each ofthe light beams respectively represents a field of view angle of −60degrees, −45 degrees, −30 degrees, −15 degrees, 0 degree, 15 degrees, 30degrees, 45 degrees, and 60 degrees.

While, in FIG. 26B, spherical aberration, astigmatism, and distortionare shown sequentially from the left, an astigmatism of 10 mm is presentat a field of view angle of about ±30 degrees, and a distortion of 12.6%is present. Further, it can be seen from FIG. 26C that a chromaticaberration of about 150 μm is present even at a field of view angle ofabout ±15 degrees.

It is generally known that two or more kinds of glass materials havingdifferent color dispersions are combined to correct chromaticaberration, and thus there exist optical systems, such as loupe opticalsystems, in which a pupil size of about 5 mm is set and variousaberrations, including chromatic aberration, are corrected within therange of ±30 degrees. The reason that such an optical system can bedesigned with ease is that because the optical system need not be usedwith the positions of the optical system and the eyeball being fixed,the position of optical axis of the optical system and the position ofthe pupil of the eyeball can always be adjusted so that they arepositioned most appropriately.

However, as an eyepiece optical system for a wearable display that isused to observe an image with the position of an display and theposition of the eyes being fixed and with separate eyepiece opticalsystems being used for the right and left eyes, there is only aneyepiece optical system having a field of view angle of about ±22.5degrees at best. In FIG. 26D, various aberrations of the optical systemshown in FIG. 26A in the cases of field of view angles of 0 degree, 7.5degrees, 15 degrees, 22.5 degrees, and 30 degrees are shown. Althoughchromatic aberration is corrected by the use of the lens combination, achromatic aberration of 200 μm and various aberrations of 400 μm arepresent at the position of field of view angle of 22.5 degrees, and itcan be seen that assuming the size recognizable by the human eye to beabout 100 μm, this condition is insufficient. Thus, it can be inferredthat to make aberrations small down to the limit recognizable by thehuman eye, a combination of only convex lenses does not suffice, and acombination of a convex lens and a concave lens is required.

However, regarding a combination of a convex lens and a concave lens,the concave lens makes the differences between the inclinations of theprincipal rays of the respective light beams from the light emittingpicture plane small and thus cannot, at a wide field of view angle,efficiently deflect diverging light beams, and thus the lens diameterhas to be made larger. On the other hand, as can be clearly seen fromthe light beams of FIG. 26A, of which optical system is constituted onlyby the convex lenses, if such eyepiece lens is applied to each of theright and left eyes, then, assuming an eye-width (the distance betweenthe right and left eyes) of 6.5 cm, the right and left eyepiece opticalsystems, even though they are constituted only by the convex lenses,overlap with each other on the nose side, and thus a nose side field ofview angle of up to about 30 degrees can only be obtained. An attempt toeliminate aberrations by combining a convex lens with a concave lensresults in the extension of the principal ray of each of the beamscoming out of the eye by the effect of the concave lens, and thus thenose side field of view becomes still smaller, which means, at best, afield of view angle of about 22.5 degrees.

Next, it will be considered how to obtain a larger field of view. Inorder to obtain an image with a high sense of reality, it is necessaryto obtain a field of view equivalent to or more than the field of viewthat is associated with the condition when a human wears glasses, and asufficient field of view angle on the nose side, in which a limit isplaced on the eyepiece lens diameter, must be secured. In order toobtain a still larger field of view angle on the nose side, thediameters of the convex lenses are to be made still larger, and glassmaterials having a higher refractive index are to be used.

Here, an example in which, to obtain a wider field of view, three convexlenses L1′, L2′, and L3′ which are arranged sequentially from theeyeball side and each of which has a curvature of 100 cm, 200 cm, and220 cm is shown in FIGS. 27A-27C. In FIG. 27A, G denotes a lightemitting picture plane, and H denotes the pupil of the human eye; aswith FIG. 26A, the lenses are made of glass material LAC7 having a lowrefractive index but having a small color dispersion. It can be seenfrom the light beams in FIG. 27A that a wide field of view of about 45degrees is obtained on the nose side within the range of 65 mm. However,as can be seen from FIG. 27B, which corresponds to FIG. 26B, while theastigmatism is improved, around the field of view angle of ±30 degrees,to be 3.5 mm, the distortion has become larger, i.e., 13.5%. Further, ascan be seen from FIG. 27C, which corresponds to FIG. 26C, a chromaticaberration of about 150 μm is present even at the field of view angle of±15 degrees. As just described, it can be seen that, with respect to anoptical system of which field of view angle is enlarged up to more than±22.5 degrees, it is very difficult to restrict the diameter of theoptical system within the eye-width, in addition to correcting variousaberrations including chromatic aberration.

Because, in the above, it has been understood that it is difficult, inthe prior art, to design an eyepiece optical system having a field ofview angle of more than ±22.5 degrees, the stages at which the presentinventor has conceived the present invention under such understandingwill now be described.

The reason that, in the prior art line of thought, the aberrations arenot improved as indicated in FIG. 27A is that with respect to the lightbeams, having their light beam paths at the lens periphery, whichcorrespond to the portions in which the field of view angle is large,the curvatures of the lenses are too high, and thus, typically, a designin which the curvatures are reduced, the aberrations are improved bycombining a concave lens, and, further, the number of lenses isincreased is performed. But, in the case of a mechanism in which botheyes are each provided with a separate eyepiece system, the lensdiameter is required to be equal to or less than 65 mm as describedabove.

In an attempt to address the above difficulties, the present inventorhas conceived that by making at least one surface of the convex lenses aconic surface, an improvement is realized. An example thereof is shownin FIG. 1. While in the optical system shown in FIG. 1A, the light beamsfrom light emitting picture plane G are focused on pupil H of the humaneye by using three convex lenses L11, L12, and L13, the back sidesurface (the surface located on the side distant from the eye) of lensL11 among those lenses, which is located nearest to the eyeball, is madea conic surface, thereby suppressing coma aberration and astigmatism,and thus it is configured such that even if the pupil position changesdue to a look-around eye action, good images can be projected into theeyeball. In an x-y-z Cartesian coordinate system with the z-axis beingthe optical axis, curved surface Z(r) of a conic surface can beexpressed:${Z(r)} = \frac{c \cdot r^{2}}{1 + \sqrt{\left\{ {1 - {\left( {1 + k} \right) \cdot c^{2} \cdot r^{2}}} \right.}}$where c is a constant representing a curvature, and r² = x² + y².

k denotes the conic constant, and k<0 is used. The optical design valuesare shown in Table 1. Note that each of the curvature radiuses of thesurfaces shown in the Tables in this specification, including Table 1,is expressed by a negative number when its curvature center is on thepupil side relative to the lens surface position and is expressed by apositive number when its curvature center is on the side of lightemitting picture plane G. In addition, the curvature radiuses and thesurface separations on the optical axis are expressed in the unit of mm,unless otherwise specified. TABLE 1 Surface Surface Curvature Separationon Surface No. Radius (mm) Optical Axis Glass Material Pupil: INFINITY12.000000 1: INFINITY 18.000000 F2_SCHOTT (L11) 2: −40.00000 2.000000Conic −0.800000 Constant K: 3: INFINITY 15.000000 SK11_SCHOTT (L12) 4:−80.00000 2.000000 5: 200.00000 15.000000 SK11_SCHOTT (L13) 6:−100.00000 22.074232 Light Emitting INFINITY 0.000000 Picture Plane G:

The spherical aberration, astigmatism, and distortion of such opticalsystem are shown in FIG. 1B. As can be seen from FIG. 1B, around thefield of view angle of ±30 degrees, the astigmatism is improved to be 3mm, and the distortion is small, i.e., 9.5%.

It can be seen from FIG. 1C, which shows the chromatic aberration of theoptical system, that a chromatic aberration of 200 μm is present even atthe field of view angle of ±15 degrees, which means a contrastingdeterioration.

However, since it has been found that the eyepiece lens system of FIG.1A has very good characteristics regarding the aberrations other thanthe chromatic aberration, a first embodiment mode of the presentinvention is, as shown in FIG. 2A, configured such that one lens surfaceof the convex lenses (L21, L22) which are located near to pupil H of theeyeball and with respect to which the deflection angles of the lightbeams are larger is made a conic surface having conic constant K<0 and,at the same time, such that, to correct the chromatic aberration, acemented lens (L23, L24) made by combining glass materials which aredifferent from each other is provided. The cemented lens is constitutedby at least two lenses; the cemented portion of the cemented lens ismade a concave surface on the pupil side; the color dispersion of thepupil side lens of the cemented lens is smaller than that of the otherlens; and the cemented lens has a convex-concave-convex form, which formhas a high chromatic aberration correcting effect. (“Convex” here meansa convex form in the direction of the pupil; “concave” means a convexform in the opposite direction. This applies throughout thisspecification, unless otherwise specified.) The optical design values ofthe optical system shown in FIG. 2A are shown in Table 2. TABLE 2Surface Surface Curvature Separation on Surface No. Radius Optical AxisGlass Material Pupil: INFINITY 12.000000 1: INFINITY 13.000000TAFD5_HOYA (L21) 2: −38.00000 0.200000 Conic −0.700000 Constant K: 3:INFINITY 9.000000 TAFD5_HOYA (L22) 4: −78.00000 0.200000 5: 138.0000018.500000 FCD1_HOYA (L23) 6: −50.00000 3.000000 FDS1_HOYA (L24) 7:91.00000 15.188265 Light Emitting INFINITY 0.000000 Picture Plane G:

The reason for having adopted such configuration is as follows: Namely,because, as described above, as opposed to general eyepiece lenses, thesystem must have a wide field of view angle, and there is a separateeyepiece lens for each of both eyes, the eyepiece lenses are required tobe constructed on the condition that they have a diameter of equal to orless than a half of the 65 mm eye-width. Thus, the lens near to pupil His constituted by a convex lens having a curvature which is as large aspossible, thereby the light beams are considerably deflected toward theoptical axis; a cemented lens for correcting chromatic aberration isincorporated in a position near to the object side, where the principalray of each of light beams runs more parallel to the optical axis; and,further, the lens surface near to light emitting picture plane G is madea concave lens so that the light beams incline toward the divergingdirection.

(It should be noted that while, in the above description, forconvenience of description, the light beams are assumed to start frompupil H and reach light emitting picture plane G, the actual light beamsproceed in the opposite direction. Hereinafter, for convenience ofdescription, light beams may also be described as if they came out ofpupil H, contrary to the fact.)

By this, the convex lens on the side of pupil H having a conic surfaceimproves the astigmatism and coma aberration arising around the lens;the chromatic aberration is corrected by the cemented lens; thedistortion is alleviated by the last surface of the cemented lens; and,a lens configuration of which lens diameter is not required to be madelarger is realized. This configuration has a significant effect ofcorrecting various aberrations without making the lens diameter largerand is effective in the case where, as a wearable display, the lensdiameter is constrained.

The spherical aberration, astigmatism, and distortion of the opticalsystem are shown in FIG. 2B. In FIG. 2A, a wide field of view angle ofabout 45 degrees is obtained on the nose side; further, the astigmatismis improved to be 3 mm around the field of view angle of ±30 degrees aswith FIG. 1B, and the distortion is as little as 9%, even compared withFIG. 1B. While the chromatic aberration of the optical system is shownin FIG. 2C, it can be seen that the chromatic aberration issignificantly improved to be less than 80 μm even at the field of viewangle of ±15 degrees.

However, the configuration of FIG. 2A still has the following problemsto be solved:

(1) When the 65 mm eye-width is considered, only a field of view angleof 45 degrees is obtained on the nose side, and a field of view angle of±60 degrees available with an eyeglass field of view is not achieved;the regions observed by both eyes are different from each other, whichcreates a sense of discomfort, and thus, a wide field of view angle of±60 degrees should be attained; and

(2) The chromatic aberration of 80 μm may be observed with the nakedeye, and the chromatic aberration should be more lessened; assuming thatthe resolution of the human eye is about 50 μm, a chromatic aberrationof 50 μm or less should also be attained.

Further, it is required that, to obtain a wide field of view angleimage, actions performed by the human eye be comprehended and that anoptical system by which an image can be observed in a state as naturalas possible be made. Accordingly, the present inventor has tried tostudy the actions performed by the human eye.

With respect to he human eye, up to an eyeglass field of view angle ofabout ±30 degrees, the eyeball laterally shifts to recognize surroundingthings. However, investigation into the prior art technology hasrevealed that optical systems having good aberration characteristicswithin ±30 degrees simply have good numerical values only with respectto the ±30 degrees in which the pupil position is not moved, and thatthere is no optical system in which the actual eyeball lateral shiftactions are considered. Thus, it has been studied how much the pupilmoves through the lateral shift action of the human eye to make clear onwhat conditions aberrations are required to be eliminated. The methodthereof will be explained with reference to FIG. 3.

As the study method, a method in which, with the eyeball and an opticalsystem being fixed, aberrations when the eyeball is moved from 0 degreeto 45 degrees are studied has been used. First, since when the eye viewcenter moves from 0 degree to 45 degrees, the pupil position rotatesaround the eyeball center as shown in FIG. 3, the picture plane image isto be observed, via an eyepiece optical system, from shifted positionsof 3.88 mm at 15 degrees, 7.5 mm at 30 degrees, and 10.6 mm at 45degrees, with the eye being directed toward the respective angledirections. In addition, it is known that while the human eye has a higheyesight at the eye view center, the eyesight at the shifted angle of ±5degrees from the eye view center deteriorates down to a half thereof,the eyesight at the shifted angle of ±10 degrees deteriorates down to afourth thereof; the eyesight at the shifted angle of ±15 degreesdeteriorates down to an eighth thereof.

Thus, the eyepiece lens is not required to have good aberrations for itsentire field of view angle, and it can be inferred that good aberrationswithin the range of ±10 degrees from the eye view center at the eye viewcenter shift angle of ±30 degrees would suffice. While the firstembodiment of the present invention (FIG. 2A) is designed so that it hasgood aberration up to about ±45-degree field of view angle, the behaviorof the aberrations at each of the eye view centers, −10 degrees, −5degrees, 0 degree, +5 degrees, and +10 degrees, when the eye view centershift angle of 30 degrees is assumed will be investigated hereinafter.

While FIG. 2D illustrates the light beams of the first embodimentoptical system when a look-around eye action is done, large aberrationsare present at the position of image plane G, as can be seen just fromthe drawing. FIG. 2E shows the results of the investigation into thechromatic aberration behaviors at the angles, −10 degrees, −5 degrees, 0degree, +5 degrees, and +10 degrees, each of which represents an angleseparation from the eye view center shift angle of 30 degrees; thevertical axis represents the lateral aberration, and the horizontal axisrepresents the height relative to the optical axis at the aperture plane(pupil position). A chromatic aberration of 200 μm is present, the otheraberrations of about 200 μm are also present, and the aberration spotdiagram (RMS value calculated from the plotted spots of variousaberrations) amounts to 400 μm, which shows that a clearly deterioratedimage results at the time of look-around eye action. (It is to be notedthat although FIG. 2A and FIG. 2D seem to show different lens systems,this is because, for convenience of explanation, only the regions of thelenses for which the light beams are required to be illustrated areillustrated, and thus both of the lens systems are identical. While,hereinafter, as with this instance, an identical lens system may beshown in different shapes depending on the light beam extent requiredfor explanation, lenses denoted by an identical reference symbolindicate the same lens.)

In other words, as a third problem to be solved, another problem to besolved, i.e., (3) Aberrations in the eye view center range of ±30degrees and at the angles separated therefrom by −10 degrees, −5degrees, 0 degree, +5 degrees, and +10 degrees should be good; whenassuming that the aberration at the eye view center is about 50 μm,performances of equal to or less than ±100 μm at ±5 degrees and equal toor less than ±200 μm at ±10 degrees should be realized,

is added, and by simultaneously clearing the above-described problems tobe solved (1)-(3), an image perfectly equivalent to the natural imageobserved by a human will be provided.

To this end, in a second embodiment of the present invention shown inFIGS. 4A-4D, a method to improve various aberrations is devised in whichto reduce the chromatic aberration, as the glass material for the convexlenses near to the pupil, a glass material having a low refractive indexbut also having a low color dispersion is used to improve the chromaticaberration and in which by making the conic coefficient k≦1, thecurvature at the lens periphery is reduced. This optical system is, asshown in FIG. 4A, constituted by convex lenses L31 and L32 and thecemented lens made by cementing convex lens L33 and concave lens L34.The optical design values thereof are shown in Table 3. TABLE 3 SurfaceSurface Curvature Separation on Surface No. Radius Optical Axis GlassMaterial Pupil: INFINITY 10.000000 1: INFINITY 11.000000 TAC8_HOYA (L31)2: −36.00000 0.200000 Conic −1.000000 Constant K: 3: INFINITY 8.000000TAC8_HOYA (L32) 4: −66.00000 0.200000 5: 210.00000 17.000000 TAF3_HOYA(L33) 6: −44.00000 3.000000 SF59_SCHOTT (L34) 7: 130.00000 19.067127Light Emitting INFINITY 0.00000 Picture Plane G:

As a result, as can be seen from FIGS. 4A and 4B, while the aberrationsof the light beams passing through the lens periphery when the pupil islocated in the center portion suffer deterioration compared with thefirst embodiment shown in FIG. 2A, the various aberrations present atthe time of 30-degree look-around eye shown in FIGS. 4C and 4D aresignificantly improved, and clearly improved spot diagrams of about 100μm at 0 degree, about 150 μm at ±5 degrees, and about 200 μm at ±10degrees can be recognized.

A third embodiment of the present invention designed in accordance withsuch idea is shown in FIGS. 5A-5D. As shown in FIG. 5A, this opticalsystem is configured such that while one lens surface of the concavelenses (L51, L52) which are located near to pupil H of the eyeball andwith respect to which the deflection angles of the light beams arelarger is made a conic surface having conic constant K<−1, the cementedlens (L53, L54) for correcting the chromatic aberration made bycombining glass materials which are different from each other isconstituted by at least two lenses; the cemented portion of the cementedlens is made a convex surface on the side of pupil H; the colordispersion of the pupil side lens of the cemented lens is smaller thanthat of the other lens; and the cemented lens has aconvex-concave-convex form, which form has a high chromatic aberrationcorrecting effect. As can be seen by comparing FIG. 4A with FIG. 5A, thethird embodiment differs from the second embodiment mainly in that thecemented portion of the cemented lens is made a convex surface on theside of pupil H.

In the third embodiment also, as with the second embodiment, theastigmatism occurring at the lens periphery is improved by convex lensL51 having the conic surface on the side of light emitting picture planeG; the chromatic aberration is corrected by the cemented lens (L53,L54); and by making the final surface a convex surface that makes thelight beams incline toward the diverging direction, the distortion isalleviated to improve the aberrations at the time of look-around eyeaction. Table 4 shows the optical design values of the optical systemshown in FIG. 5A. TABLE 4 Surface Surface Curvature Separation onSurface No. Radius Optical Axis Glass Material Pupil: INFINITY 10.0000001: INFINITY 11.000000 TAC8_HOYA (L51) 2: −36.00000 0.200000 Conic−1.000000 Constant K: 3: INFINITY 8.000000 TAC8_HOYA (L52) 4: −66.000000.200000 5: 210.00000 3.000000 SF59_SCHOTT (L53) 6: 44.00000 13.000000TAF3_HOYA (L54) 7: 130.00000 22.330761 Light Emitting INFINITY 0.000000Picture Plane G:

As a result, as can be seen from FIG. 5A, while the aberrations of thelight beams passing through the lens periphery when the pupil is locatedin the center portion suffer deterioration compared with the embodimentshown in FIG. 2A, the various aberrations present at the time of30-degree eyeball lateral shift shown in FIGS. 5B and 5C aresignificantly improved, and, as compared with the first embodiment,improved spot diagrams of about 200 μm at 0 degree, about 200 μm at ±5degrees, and about 250 μm at ±10 degrees can be recognized. However,because the cemented lens of this embodiment is made to have aconvex-concave-convex form for the above-described reason (i.e., thefinal surface being made a convex surface that makes the light beamsincline toward the diverging direction), the correction effect withrespect to the chromatic aberration is small as compared with the secondembodiment, and thus the chromatic aberration cannot be correctedcompletely, which makes an offset of about 150 μm occur.

The effect of the present invention has been examined by way of theabove-described first to third embodiment of the present invention. And,while, regarding the above-described problems to be solved, i.e.,

(1) When the 65 mm eye-width is considered, only a field of view angleof 45 degrees is obtained on the nose side, and a field of view angle of±60 degrees available with an eyeglass field of view is not achieved;the regions observed by both eyes are different from each other, whichcreates a sense of discomfort;

(2) The chromatic aberration of 80 μm may be observed with the nakedeye, and the chromatic aberration should be more lessened; and

(3) A good image in the eyeglass field of view observed by a humanshould be provided at the time of the look-around eye action,

it has been explained that improvement with respect to (3) can beachieved, problems to be solved (1) and (2) are not yet sufficientlycleared. As a reason for not being able to improve (1) and (2) in thefirst to third embodiments, it can be pointed out that the use of theconic surface for solving the problem to be solved (3) and the use of aglass material having a low color dispersion for the convex lens on thepupil side for making the chromatic aberration small have made the lightbeam deflection angles at the lens periphery small, and thus the size ofthe final light emitting picture plane G cannot be made equal to or lessthan 65 mm, the eye-width. In addition, that the last surface of thelens on the side of light emitting picture plane G for suppressing thedistortion and the aberrations is convex is also one of the reasons forwhich the size of the final light emitting picture plane G is large.

In view of the above, in a fourth embodiment of the present invention,the picture plane G itself has been made a concave surface as shown inFIG. 6A. The optical design values of the optical system shown in FIG.6A are shown in Table 5. TABLE 5 Surface Surface Curvature Separation onSurface No. Radius Optical Axis Glass Material Pupil: INFINITY 10.0000001: INFINITY 11.000000 TAFD5_HOYA (L61) 2: −30.00000 0.200000 Conic−1.100000 Constant K: 3: INFINITY 8.000000 TAFD5_HOYA (L62) 4: −66.000000.200000 5: −300.00000 12.500000 TAF5_HOYA (L63) 6: −45.00000 3.000000SNPH2_OHARA (L64) 7: 70.00000 20.190463 Light Emitting −45.000000.000000 Picture Plane G:

Calculation of various aberrations on the condition that light emittingpicture plane G is made a concave surface has revealed that withoutusing a glass material for having a low color dispersion for the convexlenses on the pupil side (L61, L62) for suppressing the chromaticaberration to be small, the good aberrations shown in FIG. 6B can beobtained even by using a glass material having a relatively largerefractive index and color dispersion and that also at the time oflook-around eye shown in FIGS. 6C and 6D, performances equivalent tothose of the third embodiment can be obtained.

What is most characteristic of this embodiment is that with lightemitting picture plane G itself being made a concave surface, the lightbeams passing through the lens periphery reach light emitting pictureplane G before they expand; with the conic constant being made to beeven smaller, i.e., −1.1, various aberrations can be improved even whenthe lateral shift of the eyeball has occurred; and, moreover, as aresult, the diameters of the lenses and light emitting picture plane Gcan be suppressed to be within the 65 mm eye-width. Through this method,it can be realized that a field of view angle of ±60 degrees is ensuredfor both eyes and, in addition, that good images are obtained even atthe time of look-around eye.

However, here arise problems relevant to the structure of light emittingpicture plane G. If light emitting picture plane G is to be constitutedby a liquid crystal device or the like, then the liquid crystal devicepicture plane is required to be curved; if with light emitting pictureplane G being made a screen, an image is to be formed from the reverseside of the screen, then the focus condition and telecentricity of theprojection optical system are also required to be considered.

A fifth embodiment of the present invention that can solve thoseproblems is shown in FIGS. 7A-7E. In this optical system, as shown inFIG. 7A, with the cemented lens (L73, L74, L75) having two cementedsurfaces being introduced, the deficiencies of chromatic aberrationcorrection associated with each of the cemented lenses of theabove-described embodiments are dissolved, and the deteriorations of theother aberrations arising therefrom are corrected, with a glass materialhaving a high refractive index used for the convex lenses (L71, L72) onthe pupil side and with the conic constant k being made still smaller,i.e., k<−1.1. The optical design values of the optical system shown inFIG. 7A are shown in Table 6. TABLE 6 Surface Surface CurvatureSeparation on Surface No. Radius Optical Axis Glass Material Pupil:INFINITY 10.000000 1: INFINITY 11.000000 TAFD5_HOYA (L71) 2: −31.000000.200000 Conic −1.450000 Constant K: 3: INFINITY 7.500000 TAFD5_HOYA(L72) 4: −66.00000 0.200000 5: INFINITY 13.000000 TAFD30_HOYA (L73) 6:−44.00000 3.000000 SNPH2_OHARA (L74) 7: 35.00000 12.000000 TAFD30_HOYA(L75) 8: 80.00000 9.568060 Light Emitting INFINITY 0.000000 PicturePlane G:

The cemented lens is constituted by the three lenses, L73, L74, and L75;the color dispersion of the lens glass material of L74 is larger thanthat of L73 and L75; and the cemented surfaces are composed of,sequentially from the side of pupil H, a concave surface and a convexsurface. Thus, large chromatic aberration can be corrected. Further,also with respect to the convex lenses (L71, L72) on the pupil side, aglass material having a high refractive index is used, which has enabledthe deflection angles of the light beams passing through the lensperiphery to be made large.

In accordance with this method, the lens diameter can be made equal toor less than the 65 mm eye-width; however, if the method is followed asit is, the aberrations at the time of look-around eye actiondeteriorate. To address this difficulty, in this embodiment, it isconfigured such that within a range satisfying the condition that thelens diameter does not exceed 65 mm, the conic constant is made stillsmaller, i.e., k=−1.45, and the surface on the side of light emittingpicture plane G of lens L75 is also made a convex surface, therebysuppressing various aberrations.

By this, good aberrations are obtained as shown in FIG. 7B, and as shownin FIGS. 7C and 7D, at the time of look-around eye also, the aberrationsare suppressed to be an aberration of less than 25 μm at the position of30-degree field of view center, an aberration of less than 50 μm even atthe positions separated from the center by ±5 degrees, and an aberrationof less than 100 μm even at the positions separated from the center by±10 degrees, and at the same time a field of view angle of ±60 degreesis obtained.

In addition, with regard to the fifth embodiment and with regard to thecase where the field of view center is located at 15 degrees, the MTF(which with respect to a image having a predetermined spatial frequency,shows in percentage the (MAX−MIN)/(MAX+MIN) values of the line/spaceamplitudes when the spatial frequency is varied) at the best focusposition of the combination of the conic surface and the chromaticaberration correcting lens is compared with the MTF at the best focusposition of the prior art system. In the drawings, T denotes thetangential, theoretical maximum value, and R denotes the radial,theoretical maximum value; X is the MTF in the X-direction, and Y is theMTF in the Y-direction. As can be clearly seen from this illustration,the embodiment has a small degree of dependence on the MTF at each ofthe frequencies and has a simple frequency characteristic. This meansthat, in the embodiment, when an image is observed, a sense ofdiscomfort due to protruding of the image or due to differing focuspositions depending on the frequencies is prevented from occurring, andthus a good image can be provided.

While, in the above, the fifth embodiment optical system is shown inFIG. 7A, various problems arise in the actual manufacture thereof.Specifically, the glass materials used for the optical elements areglass materials having a large refractive index; and thus, it is noteasy to secure the sizes of the glass materials or to process them in astable condition, which may cause cost increase. Thus, as the glassmaterial for which aspheric surface processing is required to create thelens having a conic constant of less than 0, use of SLAH66, a hardmaterial, rather than TAFD5 will facilitate processing.

In addition, with respect to the glass materials such as SNPH2, there isa problem that it is difficult, in terms of quality control, to secure apredetermined thickness. Thus, as a first modification example of thefifth embodiment, the case in which, as shown in FIG. 7F, the glassmaterial of aspheric lens L71 is changed from TAFD5 to SLAH66, and L74of the cemented lens constituted by L73, L74, and L75 is divided intothe two lens, L74A and L74B will now be described. The optical designvalues of the optical system shown in FIG. 7A are shown in Table 7. Thelens diameter of L71 is 51.0 mm; that of L72 is 58.9 mm; those of theother lenses are all 58.6 mm. TABLE 7 Surface Surface CurvatureSeparation on Surface No. Radius Optical Axis Glass Material Pupil:INFINITY 10.000000 1 INFINITY 11.000000 SLAH66_HOYA 2 31.00000 0.200000Conic Constant K: −1.3 3 INFINITY 8.500000 SLAH55_HOYA 4 66.000000.200000 5 INFINITY 10.500000 SLALH58_HOYA 6 53.00000 0.000000 753.00000 3.000000 SNPH2_HOYA 8 INFINITY 0.000000 9 INFINITY 3.000000SNPH2_HOYA 10  −42.00000 0.000000 11  −42.00000 11.000000 SLAH58_HOYA12  150.00000 9.568060 Light Emitting INFINITY 0 Picture Plane G:

In the case of the optical system shown in FIG. 7F (a modificationexample of the fifth embodiment), with the lens curvatures beingslightly changed, a performance substantially equal to that of the fifthembodiment is obtained. Both of L74A and L74B have a center thickness of3 mm; and while L74 in FIG. 7A requires a glass material thickness ofabout 25 mm, each of L74A and L74B, in contrast, requires only a glassmaterial thickness of equal to or less than 15 mm, which enables astable supply of the glass material.

In this connection, while L74A and L74B are cemented by way of a flatsurface, those lenses are here, for the sake of convenience, regarded asa single lens because those lenses are made of an identical glassmaterial. It should be noted that because also in the case, for example,where the refractive indexes of the glass materials of L74A and L74B aremade slightly different from each other or where the cemented surface ofL74A and L74B is made to have a slight curvature, a similar effect canof course be obtained, cemented lenses using such a method will all bedefined here as a three lens piece cemented lens.

As a modification example of the fifth embodiment, an example in whichthe combination of the lenses to be cemented is modified is shown inFIGS. 8A-8D as a sixth embodiment. More specifically, as shown in FIG.8A, with the cemented lens (L83, L84, L85) having two cemented surfacesbeing introduced, the deficiencies of chromatic aberration correctionassociated with each of the foregoing cemented lenses are dissolved, andthe deteriorations of the other aberrations arising therefrom arecorrected, with a glass material having a high refractive index used forthe convex lenses (L81, L82) on the pupil side and with the conicconstant k being made still smaller, i.e., k<−1.1. In this embodimentalso, the same effect as that of the fifth embodiment can be obtained.The optical design values of this optical system are shown in Table 8.TABLE 8 Surface Surface Curvature Separation on Surface No. RadiusOptical Axis Glass Material Pupil: INFINITY 10.000000 1: INFINITY11.000000 TAFD10_HOYA (L81) 2: −32.00000 0.200000 Conic −1.300000Constant K: 3: INFINITY 7.500000 TAFD10_HOYA (L82) 4: −66.00000 0.2000005: −500.00000 3.000000 SNPH2_OHARA (L83) 6: 53.00000 21.000000TAFD30_HOYA (L84) 7: −53.00000 3.000000 SNPH2_OHARA (L85) 8: 200.0000012.264784 Light Emitting INFINITY 0.000000 Picture Plane G:

The cemented lens is constituted by the three lenses, L83, L84, and L85;the color dispersion of the lens glass material of L84 is smaller thanthat of L83 and L85; and the cemented surfaces are composed of,sequentially from the side of pupil H, a convex surface and a concavesurface. Thus, large chromatic aberration can be corrected. Further,also with respect to the convex lenses (L81, L82) on the pupil side, aglass material having a high refractive index is used, which has enabledthe deflection angles of the light beams passing through the lensperiphery to be made large. In accordance with this method, the lensdiameter can be made equal to or less than the 65 mm eye-width.

However, if the method is followed as it is, the aberrations at the timeof look-around eye action deteriorate. To address this difficulty, thisembodiment is configured such that within a range satisfying thecondition that the lens diameter does not exceed 65 mm, the conicconstant is made still smaller, i.e., k=−1.3, and the last surface oflens L75 is also made a convex surface, thereby suppressing variousaberrations.

By this, the good aberrations shown in FIG. 8B are obtained, and asshown in FIGS. 8C and 8D, also after the lateral shift of the eyeball,the aberrations are suppressed to be an aberration of less than 25 μm atthe position of 30-degree field of view center, an aberration of lessthan 50 μm even at the positions separated from the center by ±5degrees, and an aberration of less than 100 μm or so even at thepositions separated from the center by ±10 degrees, and at the same timea field of view angle of ±60 degrees is obtained.

Next, light emitting picture plane G will be described. Two-dimensionalimage output devices of light emitting type, as represented by, i.e.,liquid crystal displays, are most ideal for light emitting picture planeG. However, in the present technology, there is no two-dimensional imageoutput device that is a display of 60 mm square or so and has, even ifit is magnified by the above-described eyepiece optical systems, a dotsize required to obtain a sufficient image resolution. Thus, in the caseof projecting an image from a two-dimensional image output device to thepupil with a field of view angle of ±60 degrees, it is required tocreate a high-definition image by obtaining a magnified image of theimage of a light emitting type two-dimensional image output devicehaving a very small dot size, as is performed by a projector. There arepresently various types of projectors, ranging from a type using aliquid crystal display device having a resolution matrix of 320 by 240,called QVGA, to a type in which by using three liquid crystal displaydevices having a resolution matrix of 1980 by 1024 or so, called SXGA,three color images, each of which corresponds to either one of thecolors of G, R, and B, are separately formed and then combined togetherto triple the resolution.

If a liquid crystal display device having a low resolution is utilizedas an embodiment of the present invention, the seams between the pixelsof the liquid crystal display device are to be recognized by the eye inthe case of a movie theater class screen, and the sense of reality willbe lost. Thus, when an image quality equal to or higher than that of aprojector is desired, it is indispensable to introduce the technology inwhich by using three liquid crystal display devices having a resolutionmatrix of 1980 by 1024 or more, called SXGA, three color images, each ofwhich corresponds to either one of the colors of G, R, and B, areseparately formed and then combined together to triple the resolution.

In addition, because all of the above-described eyepiece optical systemsof the present invention are configured to be nontelecentric relative tolight emitting picture plane G to result a good distortion andaberration corrections, the telecentricity conditions of the lightemitting type two-dimensional image output devices having a very smalldot size as used in the above-described projector are required to matchthe telecentricity conditions of the above-described eyepiece opticalsystems.

However, in the case of, for example, the sixth embodiment, the anglewhich the principal rays of the light beams of ±60 degree field of viewangle make with the normal to light emitting picture plane G when theprincipal rays, starting from the position of light emitting pictureplane G, reach the lens L85 of the eyepiece optical system is themaximum value of 20 degrees; and thus, assuming that the magnificationfrom the light emitting type two-dimensional image output device tolight emitting picture plane G is 3×, a nontelecentric optical system inwhich each of the light beams emitted from the respective pixels of thelight emitting type two-dimensional image output device is emitted withan NA corresponding to 60 degrees, 3-times as compared with the value of20 degrees, must be provided. This gives rise to a severe condition indesigning such an illumination mechanism for the two-dimensional imageoutput device, in view of, for example, the effective illumination angleof a liquid crystal display device or the like.

In view of the above, a method can be conceived in which a screen isprovided at the position of light emitting picture plane G; light beamsemitted from a light emitting type two-dimensional image output deviceare projected onto the screen via a relay system; and then an imagecreated on the back side of the screen with the projected image beingtransmitted through the screen is re-projected onto the retina of theeyeball by one of the above-described eyepiece optical systems. From aprior art standpoint, this method is already disclosed in JapaneseUnexamined Patent Publication Hei 7-128612 (Patent Literature No. 3);however, no technique for improving such aberrations arising at anglesof ±22.5 degrees or more as described above is described therein.

In introducing a screen this time, it is necessary to provide a screenthat provides an image to an eyepiece optical system having aninclination of 20 degrees, as a non-telecentric eyepiece optical systemhaving achieved the above-described object and that is adiffusing/transmitting type screen formed by grains smaller than thevery small dots of a resolution matrix of 1280 by 1024, called SXGA.

In the following, an example in which a diffusing glass is used as theabove-described screen will be described. It can be seen from FIG. 8Athat when the eyeball lateral shift is 30 degrees, the telecentricity isinclined (i.e., the principal is inclined) by a maximum of about ±10degrees. Thus, as the screen, a screen that makes the diverging angle ofthe light beam proceeding from each position thereon a sufficientlylarge angle so that even if the eye view direction changes depending onthe look-around eye, light rays incident in the pupil of the eyeballexist and that corresponds to a level at which the human eye cannotrecognize the roughness thereof, i.e., to the type of diverging angle A,which has a roughness of equal to or larger than 700 under theterminology of ground glass can be used adequately. Because, of course,the look-around eye angle of a human is required to be considered up toabout ±30 degrees, a screen of which light intensity distribution doesnot considerably varies within the range of about ±20 degrees ispreferably used. It is to be noted that in FIG. 8A, the inclination ofthe telecentricity (inclination of the principal ray) is even larger atthe position of the field of view angle of 60 degrees; however, becausethis portion is a portion in which the resolution of the human eye islow, the portion need not be considered.

Thus, as the screen, a screen made by applying an adhesive over apolyester film of which thickness is uniform and of which surface issmooth and then by, in a clean room, coating the film with abrasivegrains of which grain diameter is precisely controlled with micron-gradeis used. It should be noted that as the abrasive grains, an oxide or acarbide, such as silicon carbide, chromium oxide, tin oxide, titaniumoxide, magnesium oxide, and aluminum oxide, is most suitable; andabrasive grains of uniform diameter of about 0.3 to 40 μm manufacturedthrough a ultraprecision finishing are adopted.

In accordance with the screen formed in this way, the abrasive grains,opaque but uniform, can be multilayered in a random distribution andwith a predetermined thickness; the diverging angle can be made equal toor larger than ±60 degrees; even in the case of a DVD or high-definitionimage, one does not feel a sense of grains; and a field of view angle of±22.5 degrees or more can be secured. Further, the screen is desirablealso in that it can be manufactured at a low cost. In addition, thethickness of the abrasive grain layer is preferably made to be withinthe focus depth of the projected image, and it is desirable that thelayer is as thin as possible for the purpose of obtaining a sufficientilluminance.

Additionally, as the size of the abrasive grains, a mesh number canchosen among from #320 to #15000, and because a tough polyester film isused, the durability becomes high. Note that with respect to siliconcarbide, chromium oxide, tin oxide, titanium oxide, magnesium oxide, andaluminum oxide, if micron-order abrasive grains thereof are used, thescreen is to be recognized as an opaque object. In this case, theprojection illuminance on the screen is required to be made high.

Although when the above-described screen is utilized, there is an effectthat a sharp image can be obtained because the diverging angle is wideand, further, the grains on the screen are not recognizable, the lightintensity decreases to about a tenth. Accordingly, a device to increasethe projection illuminance to compensate the decrease is required. Ofcourse, if a halogen lamp, as used in a projector, is used, a sufficientilluminance can be obtained; however, in view of the appearance of thepresent invention's devices illustrated later, it is required that inthe illumination system, a light source of which size is as small aspossible and of which life is as long as possible be used. Thus, in eachof the embodiments of the present invention, two illumination systems asshown in FIGS. 8E and 8F are adopted.

FIG. 8E is a drawing showing an illumination optical system in whichhigh intensity LEDs 166 that emit blue (B) light, red (R) light, andgreen (G) light are used. As this illumination optical system, highintensity LEDs 166 for the colors of RGB, optical fiber bundles providedfor each of the respective high intensity LEDs 166, back lightillumination system 163 of which pupil position is located at the exitend of the optical fiber bundles, liquid crystal display device 169, andthree color multiplexer 162 are illustrated.

On other two side surfaces other than the above are similarly provided aliquid crystal display device, an illumination optical system, opticalfiber bundles, and high intensity LEDs. However, as each set of thethree sets of the high intensity LEDs, high intensity LEDs from whichone of the different colors emit are arranged. And, on the remaining oneside surface is provided a relay optical system described andillustrated later.

Recent progress in LCDs is remarkable; LCDs that provide a light outputof about 1 [lm] are on the market; and, future ultra-high intensity LEDsthat can provide an output of about ten times as high as that lightoutput are currently under development. In addition, LCDs provide anexcellent performance also with respect to their power consumption andlife. However, the light directivity thereof is about 15 degrees, andalso the distribution is not uniform. Moreover, a light beam having anNA of about 0.02 to 0.03 is desirable for a zoom optical system forprojecting an image of a liquid crystal display device to a screen(described later), and thus it is not easy to effectively use the lightfrom high intensity LEDs as the back light for the above-describedliquid crystal display devices.

Thus, in this embodiment, it is configured such that for each of thehigh intensity LED colors of blue (B), red (R), and green (G), one ormore high intensity LEDs 166 are provided; optical fibers 165 arerespectively disposed at the exit position of each of the LEDs; thoseoptical fibers 165 are gathered to be bundled in a circular form; andthe light is emitted from the pupil position of back light illuminationsystem 163 of the above-described liquid crystal device. Generally, thelight emitting area of the light emitting chip of a LED is about 200 μm;and an optical fiber with a core having a diameter of more than that isprovided on the light emitting plane. For example, when assuming thatthe illuminance of the LED is 1 [lm], the pupil of back lightillumination 163 has a design diameter of about 4 mm, and thus, in thecase of designing an illumination system of this size, a bundle of, inthe case of optical fibers of 0.8 mm diameter, about twenty opticalfibers can be arranged on the pupil plane. Accordingly, a uniformtwo-dimensionally light emitting illumination light having anilluminance of 20 [lm] can be emitted from the pupil position of theillumination system.

In this regard, because light beams having a predetermined angle arerepeatedly totally reflected in optical fibers 165 and proceed inoptical fibers 165, the exit angle thereof at the optical fiber exitportion (pupil plane) coincides with the incidence angle. Thus, because,as with the case of optical rod effect, light having the same NA as thatof the light incident on the optical fibers is emitted at the exitportion of the optical fibers, the light can be supplied to the zoomoptical system (described later) without the light beams being uselesslyexpanded. The illumination optical system thus serves also as anilluminance uniformizing optical system by which the uniformity isimproved. For example, because the exit angle at the pupil planedetermines the illuminated area on liquid crystal device 169, theuniformity can be adjusted through the directivity characteristics ofthe LED, the adjustment of the magnification of the optical system, andthe number of fibers.

Further, the number of the fibers led from one LED need not be one, andit can also be conceived that fibers with smaller diameter are bundledand used. In this case, because the number of fibers bundled on thepupil increases, the shape of the pupil can be made to approach acircle. Furthermore, when the fiber diameter is small, the fibers can bearranged to meet the directivity of the LED, and thus the exit angle atthe pupil plane can be made smaller.

FIG. 8F is a drawing showing an illumination optical system in whichcold cathode tubes 167 that emit blue light, red light, and green lightare used. Note that in FIG. 8F, the same constituent elements as thoseshown in FIG. 8E are denoted by the same reference numerals, anddescriptions thereof may be omitted. Cold cathode tubes can be madesmall-sized compared with hot cathode tubes and are used as back lightsof, e.g., a CRT, also from the standpoint of power consumption and life.However, such display back lights are normally implemented by way ofdiffusing light beams from a cold cathode tube by means of a diffusingplate or the like, and thus it is difficult to use them for a zoomoptical system (described later), located between a liquid crystaldevice and a screen, for which, as in this embodiment, only the lightbeams having an NA of about 0.02 to 0.03 are useable.

So, in this invention, it is configured such that for each of the colorsof blue, red, and green, one or more cold cathode tubes 167 areprovided; optical fibers 164 are disposed at the exit position of eachof the cold cathode tubes; those optical fibers 164 are gathered to bebundled in a circular form; and the light is emitted from the pupilposition of back light illumination system 163 of the above-describedliquid crystal device. Generally, the cold cathode tube has, at aminimum, a size of about 2 mm diameter and 40 mm length; reflectingmirror 168 for making the cold cathode tube have directivity isdisposed; and the fibers are arranged so that the 40 mm length span islined with them. For example, in the case of fibers of 1 mm diameter,the span is lined with forty such fibers; when such fibers are bundled,leaving substantially no space therebetween, they can be made to form acircle of about 10 mm diameter; and thus, a uniform illumination lighthaving a high illuminance can be emitted from the pupil position of theillumination system. If a required light intensity cannot be secured byone cold cathode tube, a plurality of cold cathode tubes may be used.

With, as described above, high intensity LEDs 116 or cold cathode tubes167 being used as a back light, power consumption is suppressed; becauseof the long life, one is not bothered with the light source replacementwork; and a fan or the like required when using a halogen lamp can bedispensed with, which makes it possible to realize a simple deviceconfiguration.

With reference to FIGS. 8E and 8F, the cases in which the transmissiontype liquid crystal display devices 169 are used have been explained,but in a case in which reflection type liquid crystal display devicesare used, a light source type that emits white light will be used withrespect to both of the high intensity LED and the cold cathode tube, andin accordance with a method similar to the methods shown in FIGS. 8E and8F, a light emitting plane will be formed at the pupil position of theillumination optical system.

In both of the case in which transmission type liquid crystal displaydevices are used and the case in which reflection type liquid crystaldisplay devices are used and in the case in which a light sourceemitting white light is used, it will be configured such that the lightbeam of the emitted light is thereafter divided into a red one, a blueone, and a green one by means of a three color beam splitter, and thelight beams, each having been reflected by each of the reflection typeliquid crystal display devices, are combined together again by means ofa three color multiplexing prism to emit the combined light beam towardthe zoom optical system.

Since the illumination system problem associated with the case wherelight emitting picture plane G is substituted by screen G has beenresolved, all-time new effects can be brought about under theconfiguration. As an example thereof, referring to FIG. 25, a methodwill be described in which by dividing and combing images outputted fromthe two light emitting type two-dimensional image output devices (aliquid crystal display device and a color multiplexing prism will becollectively called so) 150X and 150Y, various images are provided tothe right eye 2R and the left eye 2L. FIG. 25 shows a mechanism in whichthe two two-dimensional image output devices 150X and 150Y are used;beam splitters for combing and dividing the light beams from each of theimage output devices are provided; and with respect to the beamsplitters, with the half prism type prism 153 and the total reflectiontype (normal double-sided mirror) or total transmission type (normaltransparent body) optical member 154 being exchanged with each other,both of the above-described presentation of combined images and thepresentation of a three-dimensional image realized by separatelyprojecting images having different parallaxes to the right and left eyescan be performed.

In FIG. 25, (a) of FIG. 25 is an example in which the images x and yhaving different sizes are combined and then displayed as an identicalimage in the right and left eyes (c). Y is a high-definition outputimage and x is an output image of marginal information or image. On theother hand, (b) is an example in which the different images x and yhaving an identical size are displayed as different images in the rightand left eyes (d), and by making images x and y different images havingdifferent parallaxes, three-dimensional images can be enjoyed. (a) and(b) of FIG. 25 show the optical paths of light beams x and y when halfmirror prism 153 that combines the light beam x outputted fromtwo-dimensional image output device 150X and the light beam y outputtedfrom two-dimensional image output device 150Y and optical member 154 (inthis case, a normal transparent body) designed so that the optical paththereof coincides with that of half mirror prism 153 are exchanged witheach other.

In (a) of FIG. 25, the light beam of image y outputted fromtwo-dimensional image output device 150Y is, by optical relay mechanism151Y and optical zoom mechanisms 152X and 152Y, zoomed down on screen149L and 149R to a size corresponding to the resolution of the outputimage of the content. On the other hand, the light beam x outputted fromtwo-dimensional image output device 150X is, by optical relay mechanism151X and optical zoom mechanisms 152X and 152Y, zoomed up on screen 149Land 149R to a full field of view image. Those light beams, y and x, arerespectively divided and combined by half prism 153, and the combinedimages are respectively, as light beams x and y, projected as anidentical image (c) on the retina of the left eyeball 2L and on theretina of the right eyeball 2R.

In contrast, in (a) of FIG. 25, the light beam y outputted fromtwo-dimensional image output device 150Y is, by optical relay mechanism151Y and optical zoom mechanism 152Y, zoomed up with a predeterminedimage size on screen 149L. On the other hand, the light beam x outputtedfrom two-dimensional image output device 150X is, by optical relaymechanism 151X and optical zoom mechanism 152X, zoomed up, as light beamx having the same size as that of light beam y, on screen 149R. Thoselight beams, y and x, pass through optical member 154 without beingdivided or combined by it and are separately projected, as imagesindependent of each other, on the retina of the left eyeball 2L and onthe retina of the right eyeball 2R by the above-described eyepieceoptical system, not shown, which make one enjoy three-dimensional imagescreated by parallax.

It is to be noted that such an eyepiece optical system as shown in,e.g., FIG. 8A, though not shown, is arranged between screen 149L and theright eyeball 2L and between screen 149R and the right eyeball 2R, andthus screen 149L and screen 149R correspond to light emitting pictureplane G in, e.g., FIG. 8A.

In the example, both of the images are high-definition images utilizingSXGA liquid crystal display devices, and even in the marginal imageportion as indicated in (c), sharp images can be obtained. By virtue ofthis, assuming, for example, that light beam in (c) is a screen image ina movie theater, a marginal image including the audience in the movietheater may be provided as the marginal image x. Since the image qualityof the marginal image is good, one can enjoy a sense of reality, as ifhe or she were actually in the movie theater, which results an effectthat one can view the images as perspective images. Additionally,because with only two SXGA liquid crystal display devices, the sameperformance as that of the above-described mechanism having a total offour liquid crystal display devices, there is the effect that the costand the size are reduced.

While, as described above, by projecting the images outputted from thelight emitting type two-dimensional image display devices on theabove-described screen by means of the zoom optical systems, variousadvantages are obtained, discussions as to how much range of zoommagnification should be considered will follow.

First, assuming the case where a field of view angle of ±60 degree is tobe secured and the images are to have on the screen a size of 65 mm, thesame as the eye-width, a magnifying zoom mechanism of about 3 times thatmagnifies a 20 mm to 23 mm image to a 65 mm image will be requiredbecause the picture plane size of the two-dimensional image displaydevice is about 0.8 to 0.9 inch. On the other hand, relative to thehigh-definition image compatible SXGA liquid crystal display device, inview of television setting, the setting by which dots become completelyinvisible corresponds to the case where a television of 40 to 50 inchesis viewed from a position a few meters distant from the television.Thus, when it is configured such that the picture plane size can beoptically reduced down to ±18 degrees, as the field of view angle, andsuch that, with respect to picture planes smaller than that, the pictureplane size is reduced by electrical switching, dots cannot berecognized, and the fine dots of the SXGA liquid crystal display devicecan be effectively used. Accordingly, as the zoom magnification, a zoommagnification of about tan(60°)/tan(18°)=4 to 5 times will be required.This corresponds to, as the field angle, 13 to 65 mm, and, in view ofthe size of the two-dimensional liquid crystal display device, a zoommechanism addressing a range ranging from reduction to magnificationmust be provided.

In the following, as a seventh embodiment, there will be described,referring to FIGS. 9-11, a zoom optical system example that projects animage located on a liquid crystal surface onto a screen that is usedwhen, such an eyepiece lens that leads a screen image of 63 mm size, aslight emitting picture plane G, to the user's eye with a field of viewangle of ±60 degrees is used. This zoom optical system is a 5-time zoomsystem that can change the image on the SXGA liquid crystal displaydevice so that the size on light emitting picture plane G is in a rangeof 12.4 mm to 63.3 mm.

Generally, zoom optical systems are used in cameras or photographyenlargers; their object plane or projection plane is located distanttherefrom; further, most of them are used for magnifying purposes. Incontrast, because the zoom optical system related to the presentinvention has a short distance between the object plane and theprojection plane and, at the same time, is required to cover themagnification change of up to 5 times, ranging from reduction tomagnification, the design thereof is required to address the problemthat the chromatic aberration characteristics change between itsreduction conditions and its magnification conditions.

To solve the problem, as shown in FIGS. 9A, 10A, and 11A (each of whichshows an identical optical system, except that their zoom conditionsdiffer from each other), it is configured such that at least twocemented lenses are used in the lens group that is constituted by,sequentially from the side of liquid crystal display device image outputplane OBJ, L91-L96, to, within the optical system up to the pupil plane(located at the same position as that of the front surface of lens L97),completely correct the chromatic aberration. On the pupil plane isprovided aperture stop STO, and with the closing and opening motionsthereof, the illuminance on screen G can be varied as required. It isconfigured such that with the cemented lens (L91, L92) being arranged atthe position up to which no intervening lens exists between liquidcrystal display device image output plane OBJ and the cemented lens andwith the cemented lens (L95, L96) being arranged in the vicinity of thepupil plane, the image height-induced chromatic aberration is correctedby cemented lens (L91, L92), and the chromatic aberration related to thefocus direction is corrected by the cemented lens (L95, L96). The reasonthat there is provided a long path light beam between liquid crystaldisplay device image output plane OBJ and the pupil plane is that it isintended that by making the curvatures of each lenses small, variousaberrations are kept as low as possible.

It should be noted that in FIGS. 9A, 10A, and 11A, liquid crystaldisplay device image output plane OBJ is not illustrated, and only theoptical system for one eye is illustrated. In the case where as theliquid crystal display devices, only one liquid crystal display deviceis used in common for both eyes, the light from liquid crystal displaydevice image output plane OBJ is divided into a light for the right eyeand a light for the left eye by using a half prism or a half mirror, andeach of the lights is inputted to one of the optical systems, as shownin FIGS. 9A, 10A, and 11A, which are respectively provided for each eye.This technique is a well-known one and thus will not require detaileddescription.

The lens group for performing zoom operation will be described next. Thezoom system is constituted by the cemented lens (L97, L98) and thecemented lens (L99, L9A), each of them is a concave lens. This isbecause a combination of concave lenses is necessary to give rise to the5-time magnification change. The reason for this is that while themagnification of the zoom system is changed by one concave lens, thefocus position moves in response to the magnification change, and thus,another concave lens is necessary to bring back the moved focus positionto the original position. Those concave lenses are synchronously movedsuch that the magnification can be changed and the focus position doesnot move. While, of course, even with a combination of a concave lensand a convex lens, such performance can be brought about, the twoconcave lens combination makes the magnification changeable rangelarger, the design thereof is easier.

The former cemented lens (L97, L98) is used for determining the focusposition, the latter cemented lens (L99, L9A) for changing themagnification. Because those cemented lenses move between the fixedlenses L96 and L9B, the chromatic aberration occurring conditions differdepending upon the moved positions thereof, and thus the chromaticaberration cannot be corrected over the entire magnification range.Thus, the cemented lens (L9D, L9E) is added, the lens materials and thecurvatures of the cemented surface of the cemented lens are set so thatat each magnification condition, the chromatic aberration and the otheraberrations are successfully corrected. The optical design values ofthis optical system are shown in Table 9. TABLE 9 Lateral Picture PlaneSize 12.4 mm Surface Surface Curvature Separation Surface No. Radius onOptical Axis RMD Glass Material OBJ: INFINITY 97.000000  1: −300.000003.000000 SNPH2_OHARA (L91)  2: 195.00000 2.000000 TAFD30_HOYA (L92)  3:−300.00000 1.000000  4: 200.00000 5.000000 TAFD30_HOYA (L93)  5:−400.00000 1.000000  6: 90.00000 5.000000 TAFD30_HOYA (L94)  7:115.00000 105.000000  8: 40.00000 5.000000 TAFD30_HOYA (L95)  9:−31.00000 3.000000 SNPH2_OHARA (L96) 10: −135.00000 0.000000 STO:INFINITY 0.500000 12: −38.00000 5.000000 TAFD30_HOYA (L97) 13: 25.000003.000000 SNPH2_OHARA (L98) 14: 98.00000 3.430000 15: −38.00000 5.000000TAFD30_HOYA (L99) 16: 28.00000 3.000000 SNPH2_OHARA (L9A) 17: 86.0000034.670000 18: −151.00000 3.000000 TAFD30_HOYA (L9B) 19: −46.000001.000000 20: 300.00000 6.000000 TAFD30_HOYA (L9C) 21: −150.000001.000000 22: 200.00000 5.000000 TAFD30_HOYA (L9D) 23: −63.00000 5.000000SNPH2_OHARA (L9E) 24: 200.00000 115.000000 25: INFINITY 3.000000TAFD30_HOYA (L9F) 26: 180.00000 5.000000 SNPH2_OHARA (L9G) 27: INFINITY10.772097 Light Emitting INFINITY 0.000000 Picture Plane G:

In FIG. 9A is shown the optical drawing that illustrates, with respectto the seventh embodiment designed under those design conditions, theleast magnification system having an image size of 12.4 mm. As anoptical system, the principal rays of the image projected on screen Gare nontelecentric in the converging direction. FIG. 9B shows thechromatic aberration, astigmatism, and distortion of the optical system,which indicates good results. Further, while FIG. 9C shows the spotdiagrams, and FIG. 9D shows lateral aberration plot output drawings foreach of the image heights, aberrations of less than 35 μm are obtainedover the entire image height range, and thus it can be seen that a goodimage quality is obtained.

Next, in FIG. 10A is shown the optical drawing in which the image sizeis 25.3 mm and which is in a zoom state of approximately 2.5 timescompared with the state shown in FIG. 9A. By changing the distancebetween lens L96 and lens L97 from 0.5 mm to 8.38 mm and changing thedistance between lens L98 and lens L99 from 3.43 mm to 6.5 mm, a zoom ofa little less than 2 times is realized. The optical design values ofthis optical system are shown in Table 10. TABLE 10 Lateral PicturePlane Size 25.13 mm Surface Surface Curvature Separation Surface No.Radius on Optical Axis RMD Glass Material OBJ: INFINITY 97.000000  1:−300.00000 3.000000 SNPH2_OHARA (L91)  2: 195.00000 2.000000 TAFD30_HOYA(L92)  3: −300.00000 1.000000  4: 200.00000 5.000000 TAFD30_HOYA (L93) 5: −400.00000 1.000000  6: 90.00000 5.000000 TAFD30_HOYA (L94)  7:115.00000 105.000000  8: 40.00000 5.000000 TAFD30_HOYA (L95)  9:−31.00000 3.000000 SNPH2_OHARA (L96) 10: −135.00000 0.000000 STO:INFINITY 8.380000 12: −38.00000 5.000000 TAFD30_HOYA (L97) 13: 25.000003.000000 SNPH2_OHARA (L98) 14: 98.00000 6.500000 15: −38.00000 5.000000TAFD30_HOYA (L99) 16: 28.00000 3.000000 SNPH2_OHARA (L9A) 17: 86.0000023.720000 18: −151.00000 3.000000 TAFD30_HOYA (L9B) 19: −46.000001.000000 20: 300.00000 6.000000 TAFD30_HOYA (L9C) 21: −150.000001.000000 22: 200.00000 5.000000 TAFD30_HOYA (L9D) 23: −63.00000 5.000000SNPH2_OHARA (L9E) 24: 200.00000 115.000000 25: INFINITY 3.000000TAFD30_HOYA (L9F) 26: 180.00000 5.000000 SNPH2_OHARA (L9G) 27: INFINITY10.749815 Light Emitting INFINITY 0.000000 Picture Plane G:

As an optical system, the principal rays of the image projected onscreen G are nearly nontelecentric or slightly nontelecentric in thediverging direction. FIG. 10B shows the chromatic aberration,astigmatism, and distortion of the optical system, which indicates goodresults. Further, while FIG. 10C shows the spot diagrams, and FIG. 10Dshows lateral aberration plot output drawings, aberrations of less than50 μm are obtained over the entire image height range, and thus it canbe seen that a good image quality is obtained. However, with comparativereference to the lateral aberration plot output drawings of FIGS. 9D and10D, it can be clearly seen that the characteristics differtherebetween.

Next, in FIG. 11A is shown the optical drawing in which the image sizeis 63.6 mm and which is in a zoom state of approximately 5 timescompared with the state shown in FIG. 9A. By changing the distancebetween lens L96 and lens L97 from 0.5 mm to 10.68 mm and changing thedistance between lens L98 and lens L99 from 3.43 mm to 27.0 mm, a zoomof 5 times is realized. As an optical system, the principal rays of theimage projected on screen G are significantly nontelecentric in thediverging direction; and, in the case where cemented lens L9F, L9G isnot included, it has been recognized, by outputting as before the spotdiagrams and lateral aberration plot output drawings, that theaberrations are large, as was expected, and a chromatic aberration ofabout 100 μm remains.

In contrast to normal camera zooms, an optical system can be arranged inthe vicinity of the object plane in the present invention; and so, bytaking advantage of this fact, it is configured such that with thecemented lens (L9F, L9G) being disposed in the vicinity of screen G thechromatic aberration can be corrected when the field angle becomeslarge. Although not having been described, the same cemented lens (L9F,L9G) is already present in FIGS. 9A and 10A. It has been ascertainedthat when the field angle is small, this cemented lens (L9F, L9G) doesnot significantly affect the aberrations. The optical design values ofthe optical system shown in FIG. 11A are shown in Table 11. TABLE 11Lateral Picture Plane Size 63.6 mm Surface Surface Curvature Separationon Surface No. Radius Optical Axis RMD Glass Material OBJ: INFINITY97.000000  1: −300.00000 3.000000 SNPH2_OHARA (L91)  2: 195.000002.000000 TAFD30_HOYA (L92)  3: −300.00000 1.000000  4: 200.000005.000000 TAFD30_HOYA (L93)  5: −400.00000 1.000000  6: 90.00000 5.000000TAFD30_HOYA (L94)  7: 115.00000 105.000000  8: 40.00000 5.000000TAFD30_HOYA (L95)  9: −31.00000 3.000000 SNPH2_OHARA(L96) 10: −135.000000.000000 STO: INFINITY 10.680000 12: −38.00000 5.000000 TAFD30_HOYA(L97) 13: 25.00000 3.000000 SNPH2_OHARA (L98) 14: 98.00000 27.000000 15:−38.00000 5.000000 TAFD30_HOYA (L99) 16: 28.00000 3.000000 SNPH2_OHARA(L9A) 17: 86.00000 0.920000 18: −151.00000 3.000000 TAFD30_HOYA (L9B)19: −46.00000 1.000000 20: 300.00000 6.000000 TAFD30_HOYA (L9C) 21:−150.00000 1.000000 22: 200.00000 5.000000 TAFD30_HOYA (L9D) 23:−63.00000 5.000000 SNPH2_OHARA (L9E) 24: 200.00000 115.000000 25:INFINITY 3.000000 TAFD30_HOYA (L9F) 26: 180.00000 5.000000 SNPH2_OHARA(L9G) 27: INFINITY 10.772577 Light Emitting INFINITY 0.000000 PicturePlane G

FIG. 11B shows the chromatic aberration, astigmatism, and distortion ofthis optical system, which indicates good results; while FIG. 11C showsthe spot diagrams, and FIG. 11D shows lateral aberration plot outputdrawings, aberrations of less than 50 μm are obtained within the imageheight of 0.5 (in terms of field of view angle, ±30 degrees), and spotdiagrams of less than 80 μm are obtained even in the condition of theimage height of 1 (in terms of field of view angle, ±60 degrees), andthus it can be seen that a good image quality is obtained. As describedabove, while with comparative reference to the lateral aberration plotoutput drawings of FIGS. 9D, 10D, and 11D, it can be clearly seen thatthe characteristics differ therebetween in a three-stage manner, goodprojection images are obtained over the entire variable magnificationrange, with the above-described chromatic aberration correction throughthe five cemented lenses being realized.

Next, referring to FIGS. 12A-12H, a zoom optical system example with ahigher performance used in an eighth embodiment of the present inventionwill be described.

The foregoing descriptions have been made by referring to only the spotdiagrams and the lateral aberration plot drawings; however, as a matterof fact, image height- and color-induced aberrations each have theirrespective best positions in the focus direction, and thus, theestimation is required to be done at the best position. Further, animage magnified by the present zoom system is observed, with the imagebeing further magnified by an eyepiece optical system, and thus,assuming for example that the liquid crystal screen is within a circleof 22.1 mm diameter and that the aspect ration thereof is 16:9 tocalculate the liquid crystal portion, the liquid crystal panel is tohave a horizontal size of 19.26 mm and a vertical size of 10.83 mm. Inother words, in the case of 1280 pixels, the pixels each have ahorizontal size of 19.26 mm/1280=15 μm and a vertical size of 15 μm; andthus, to resolve this pitch, the zoom optical system is required to havea resolution of, in terms of pitch, 30 μm.

The aberration estimation can be implemented by calculating at the bestfocus position the MTF of, in terms of frequency,1000/((15+14.3)/2)=34.13 Hz. However, in the case of an MTF, there is aresolution limit, and when the NA (numerical aperture) is made small,the image itself cannot be resolved, however the lateral aberration andthe chromatic aberration are good. Thus, making the NA large isimportant for the optical system and is also advantageous for obtaininga larger amount of light. However, generally, when the NA is made large,an optical system is significantly affected by, e.g., the sphericalaberrations of the lenses included in the optical system, which alsocauses the MTF deteriorate.

So, in the eighth embodiment optical system, a chromatic aberrationcorrecting lens is incorporated just before the screen, as describedabove, and, at the same time, a curved surface of the lens having largecurvatures located immediately after the moving zoom optical system isconstituted by a conic surface, described above. By this, the sphericalaberrations of the light beams passing through the lens peripheryimprove, and thus good aberration characteristics can be obtained with alarge NA. Tables 12 and 13 show the optical design values of the eighthembodiment optical system. Tables 12 and 13 constitute originally asingle table, but because such single table cannot be included in asingle page, it is divided into the two tables. TABLE 12 Surface No.Curvature Lens Thickness Glass Material Effective Radius Lens Size NoteLiquid Crystal 97 Distance between lens and LCD device Display DeviceSurface S1 −350 3 SNPH2_OHARA 11.7308 S2, S3 194 2 SLAH58_OHARA 11.8343Cemented surface S4 −350 11.8789 25.7578 1 Lens distance S5 200 5SLAH58_OHARA 11.9231 25.8462 S6 −400 11.8654 1 Lens distance S7 90 4SLAH58_OHARA 11.7667 25.5334 S8 115 11.4302 110 Distance between lensand pupil 10 Lens distance S9 40.8 3 SLAH58_OHARA 2.931 S10, S11 −24 3.5SNPH2_OHARA 2.9601 Cemented surface S12 −70 3.0075 8.015 Variable 1 Lensdistance S13 −38 5 SLAH58_OHARA 2.9937 S14, S15 23.2 3 SNPH2_OHARA3.1501 Cemented surface S16 98 3.2234 8.4468 Variable 1 Lens distanceS17 −38 5 SLAH58_OHARA 6.3685 S18, S19 30 3 SNPH2_OHARA 7.1443 Cementedsurface S20 86 7.4226 16.8452 Variable 50 Lens distance

TABLE 13 Surface No. Curvature Lens Thickness Glass Material EffectiveRadius Lens Size Note S21 −60 4 SLAH66_OHARA 13.5593 S22 −50 14.299444.6 Conic surface: K = −0.235 0.5 Lens distance S23 500 3 SLAH58_OHARA14.7214 S24 −125 14.8457 31.6914 0.5 Lens distance S25 200 3 SNPH2_OHARA14.8804 31.7608 S26, S27 53 5 SLAH58_OHARA 14.7602 Cemented surface S28−198 14.7108 0.5 Prism distance 32 SLAH58_OHARA 14.5996 32 Prism orhalf-mirror 0.5 Prism distance 32 SLAH58_OHARA 14.0066 32 Prism orhalf-mirror 0.5 Prism distance 32 SLAH58_OHARA 15.4218 32 Prism or cubicglass 3 Lens distance S29 −80 3 SLAH58_OHARA 15.5415 S30 −60 15.865333.7306 1.5 Lens distance S31 −140 3 SLAH58_OHARA 15.9076 S32 16016.1997 34.3994 4 Lens distance S33 −80 3 SLAH58_OHARA 16.509 S34, S35−61 3 SNPH2_OHARA 16.9972 Cemented surface S36 −79.5 17.7256 37.4512 57Lens distance S37 −80 6 SNPH2_OHARA 28.4376 S38, S39 −52 3 SLAH58_OHARA29.0976 Cemented surface S40 −80 30.7272 60 2.19623 Lens distance LightEmitting INFINITY 0 Picture Plane G:

Here is used a lens of which S22 surface (the image plane side surfaceof lens LAB) is a conic one having a conic constant of −0.235, and a5-time zoom mechanism of which NA is made up to 0.025 is realized.

Note that in the foregoing tables, to specify the glass materials, thenotation “product name (code name) maker name” is used. The refractiveindexes of each glass materials are shown in Table 14. Among those glassmaterials, SLAH66 is used as a glass material that can be fabricated inan aspheric form with ease. TABLE 14 Refractive Index for EachWavelength Product Name 1014 MAKER CODES nm 852.1 nm 706.5 nm 656.3 nm587.6 nm 546.1 nm 486.1 nm 435.8 nm 404.7 nm 365 nm SCHOTT F2 1.602791.60671 1.61227 1.61503 1.62004 1.62408 1.63208 1.64202 1.65064 1.66623SCHOTT SK11 1.5533 1.55597 1.55939 1.56101 1.56384 1.56605 1.570281.5753 1.57946 1.58653 HOYA TAFD5 1.81445 1.81928 1.82594 1.82919 1.8531.83962 1.84862 1.85955 1.86881 1.88494 HOYA FCD1 1.49008 1.491821.49408 1.49514 1.497 1.49845 1.50123 1.50451 1.50721 1.51175 HOYA EFDS11.88185 1.89064 1.90366 1.91038 1.92286 1.93323 1.95457 1.98281 2.00922.06216 HOYA TAC8 1.71407 1.71788 1.72279 1.7251 1.72916 1.73234 1.738441.74571 1.75176 1.76205 HOYA TAF3 1.78551 1.79001 1.79607 1.799 1.80421.80831 1.8163 1.82595 1.83408 1.84819 SCHOTT SF59 1.90974 1.918561.93218 1.93927 1.9525 1.96349 1.98604 2.01557 2.04269 2.09604 HOYA TAF51.79722 1.80172 1.8078 1.81074 1.816 1.82017 1.82827 1.83801 1.846191.86034 OHARA SNPH2 1.87807 1.88758 1.90181 1.90916 1.92286 1.934291.95799 1.98972 2.01976 2.08215 HOYA TAFD30 1.8606 1.86576 1.872991.87657 1.883 1.88814 1.89821 1.91045 1.92081 1.93892 HOYA TAFD101.79597 1.80063 1.80695 1.81002 1.8155 1.81986 1.82833 1.8386 1.847271.86235 OHARA SLAH58 1.86054 1.86572 1.87298 1.87656 1.883 1.888151.89822 1.9105 1.92092 1.93917 OHARA SLAH66 1.75541 1.7596 1.765141.7678 1.7725 1.77621 1.78337 1.79197 1.79917 1.81158

FIG. 12A shows the zoom statuses of such optical system: (a) is thestatus when the field angle size is 18.5 mm; (b) is the status when thefield angle size is 31.92 mm; (c) is the status when the field anglesize is 63.13 mm. In FIG. 12A, LA1-LAK denote lenses; P denotes an R-G-Bthree color multiplexer; HM denotes a half mirror; P3 denotes a totalreflection prism; GL denotes an optical path length adjusting glass.Note that with respect to the half mirror and the total reflectionprism, for convenience of description, the optical path is illustratedas if the light path was not folded and the light traveled straight.

Each of the combinations of lenses LA1 and LA2, lenses LA5 and LA6,lenses LA7 and LA8, lenses LA9 and LAA, lenses LAD and LAE, lenses LAHand LAI, and lenses LAJ and LAK is a cemented lens, and with thepositions of the cemented lens combination of LA7 and LA8 and thecemented lens combination of LA9 and LAA being adjusted, the zoom systemis realized. FIG. 12B shows as before the spot diagrams of the lateralaberration and the chromatic aberration, and (a), (b), and (c)respectively correspond to (a), (b), and (c) of FIG. 12A.

In FIGS. 12C, 12D, and 12E are shown MTFs on an image height-by-imageheight basis when the focus position is altered. FIG. 12C shows the MTFchange of the case in which an optical system using the zoom opticalsystem shown in FIG. 12A and the fifth embodiment eyepiece lens is usedand the focus position is varied. The simulation condition thereof isthat the spatial frequency of the object side image is 33 cycles/mm, theNA is 0.025, and the field of view direction is 18.5 degrees. X showsthe ideal MTF change (resolution limit) in the case where the opticalsystem is aberration free and the light intensity changes in thedirection perpendicular to the image height direction; Y shows the idealMTF change (resolution limit) in the case where the optical system isaberration free and the light intensity changes in the same direction asthe image height direction. And, the thin dotted line represents the MTFin the X-direction (the direction perpendicular to the image heightdirection) in the case of 0.25 image height; the thick dotted linerepresents the MTF in the Y-direction (the direction parallel to theimage height direction) in the case of 0.25 image height; the thicksolid line represents the MTF in the X-direction (the directionperpendicular to the image height direction) in the case of 0.5 imageheight; the thin solid line represents the MTF in the Y-direction (thedirection parallel to the image height direction) in the case of 0.5image height; the thin dashed line represents the MTF in the X-direction(the direction perpendicular to the image height direction) in the caseof 0.75 image height; the thick dashed line represents the MTF in theY-direction (the direction parallel to the image height direction) inthe case of 0.75 image height; the thin chain double-dashed linerepresents the MTF in the X-direction (the direction perpendicular tothe image height direction) in the case of 1.0 image height; the thickchain double-dashed line represents the MTF in the Y-direction (thedirection parallel to the image height direction) in the case of 1.0image height. Note that the horizontal axis scale represents thedistance from an appropriate reference position.

Similarly, the simulation condition of FIG. 12D is that the spatialfrequency of the object side image is 21 cycles/mm, and the field ofview direction is 31.92 degrees; and the meanings of the lines are thesame as in FIG. 12C. Further, the simulation condition of FIG. 12E isthat the spatial frequency of the object side image is 8 cycles/mm, andthe field of view direction is 60.13 degrees; and the meanings of thelines are the same as in FIG. 12C. Note that the NA is 0.025 in both ofFIGS. 12D and 12E.

As can be seen from the above, by altering the focus position, there canbe found a position at which the MTF value is more than 0.3 at everyimage height. In this regard, experience shows that when the MTF valueis more than 0.3, a sufficient resolution can be obtained in viewingimages. Thus, it can be seen that in the eighth embodiment zoom opticalsystem, a sufficient resolution is obtained for every image height.

Those things are summarized in FIG. 12F, and the evaluation frequenciesare determined therein based on the above-described liquid crystaldevice size and the person having an eyesight of 1.0 who can recognizethe gap of 1.5 mm C letter located at a distance of 5 m.

Referring to FIG. 12F, in the case of the field of view angle of 18.5degrees (condition 1), the MTF is, even in the case of 1.0 image height,31.5, which exceeds 30%. Also, in the case of the field of view angle of31.92 degrees (condition 6), the MTF is, even in the case of 1.0 imageheight, 31.1, which exceeds 30%. When the field of view angle is morethan 34.28 degrees, the MTF in the case of 1.0 image height becomes lessthan 30%; however, as a matter of course and as described above, at thetime of look-around eye action, the field of view angle is more than 45degrees, which exceeds the effective lens diameter, and thus imagescannot be observed directly. Since it is known that the human eye'seyesight decreases significantly at the regions other than the field ofview center region, it is configured such that relative to theaberrations of more than 45% that is to be marginal images, theaberrations of the image heights of 0 to 0.5 are set to be more than40%. Further, while FIG. 12G and FIG. 12H show the MTFs relative to eachevaluation frequencies in the case of 18.50 degree field of view angleand in the case of 31.92 degree field of view angle, respectively, thestable frequency characteristics are obtained, with the conic surfacebeing used and with the chromatic aberration correcting lens being usedin the vicinity of the screen.

While the eighth embodiment of the present invention has been describedusing FIG. 12A-12H in the above, in FIG. 13A-13C is shown an outlineconfiguration drawing in which, in connection with the image displaydevice for both eyes shown in FIG. 25, the zoom optical system of theeighth embodiment of the present invention is applied to zoom opticalsystems 152X and 152Y; in FIG. 13D is shown an example implementing theconfiguration shown in FIG. 25, by using the eyepiece lens of the fifthembodiment of the present invention, the zoom optical systems 152X and152Y (of which configuration is partially omitted) of the eighthembodiment of the present invention, two-dimensional image outputdevices 150X and 150Y, and screens 149L and 149R coated, in a cleanroom, with abrasive grains of which grain diameter is preciselycontrolled with micron-grade.

In FIG. 13A, the eighth embodiment zoom optical system is folded and ismade a zoom optical system for the left eye output use; in FIG. 13B, theeighth embodiment zoom optical system is folded and is made a zoomoptical system for the right eye output use. When those systems arecombined, the mechanism, as shown in FIG. 13(c), that provides differentimages to both eyes results; and when half prism or half mirror HM isused as the dividing/combining optical system, the center highresolution image information supplying image and the marginalinformation supplying image, each having mutually different sizes, canbe simultaneously outputted to both eyes, with the magnification of thezoom optical system shown in FIG. 13A and the magnification of the zoomoptical system shown in FIG. 13B being made different from each other.

In those figures, P1, P2, and P3 are total reflection prisms; withrespect to total reflection prism P1, the light beams are reflectedtwice, and the resultant optical axis is parallel to the originaloptical axis. With respect to total reflection prisms P1 and P2, theoptical path is deflected by 90 degrees. Optical path length adjustingglass GL adjusts the optical path differences between the light beamsthat pass through prism P1 and the light beams that pass through prismP3 and is for making it possible to form the optical systems for botheyes by the same optical system. Further, as shown in FIG. 13C, R-G-Bthree color multiplexer prism P is for combining the lights from threeliquid crystal devices, each for each of the colors of R, B, and G andsending the combined light, as a single light, into the optical system.

All of the binocular type optical systems have a structure in whichrelative to the reflecting surface of the above-described half mirror orhalf prism HM, the optical path lengths are the same; the maximum imagesize on light emitting picture plane G is 65 mm; and there are the samenumber of reflecting surfaces. Accordingly, a space saving configurationis realized, and also a configuration that facilitates commonality ofcomponents and provision of common images to both eyes is realized. FIG.13D shows an outline of the entire optical system made by combining theoptical system shown in FIG. 12C and the optical system shown in FIG. 8.In FIG. 13D, E denotes eyeballs.

The above-described configuration of FIG. 13D brings about new effectswhen viewing the same image with both eyes. With respect to the device,like this one, that projects independent screen images to both eyes bymeans of eyepiece lenses, distortions occurring on the right side andthe left side can be made to follow the same condition by making theoptical center distance between each of the eyepiece lenses coincidewith the eye-width, and thus, the sense of discomfort and the eyestraincaused when viewing different images with both eyes can be completelyremoved. However, because the human eye-width differs in individuals,ranging from about 5.5 cm to 7.5 cm, the distance between the right sideand left side overall optical systems ranging from the liquid crystaldisplay devices to the eyepiece optical systems is preferably changed tomeet the observer's eye-width. When only a part of the optical systemsis moved or when the image output position is electrically changed, theaberration conditions on the left and right sides differ from eachother, resulting in different images, and thus the sense of discomfortand the eyestrain caused when viewing different images with both eyescannot be fully removed.

FIG. 13E shows a configuration example of an optical system thatresolves such problems. In this configuration, the total reflectionprism P1 shown in, e.g., FIG. 13C is divided into the two totalreflection prisms P4 and P5. Further, it is configured such that totalreflection prism P2 and half prism or half mirror HM are fixed; totalreflection prism P3 and optical path difference adjusting glass GL canbe moved as an integral unit in the right and left directions of thedrawing; and total reflection prism P5 can also be moved in the rightand left directions of the drawing. LR denotes in a simplified mannerthe right eye-use optical system; LL the left eye-use optical system. Asclearly seen from comparative reference to (a) and (b) of the figure,when total reflection prism P3 and optical path difference adjustingglass GL are moved as an integral unit in the right and left directionsof the drawing, the optical length up to the right eye-use opticalsystem LR does not change, and only the optical axis position can bechanged (in the up and down directions of the drawing). Further, whentotal reflection prism P5 is moved in the right and left directions ofthe drawing, the optical length up to the left eye-use optical system LLdoes not change, and only the optical axis position can be changed (inthe up and down directions of the drawing).

While in FIG. 13D, the optical system is illustrated in a simplifiedmanner for the purpose of understandability, a mechanism having a totaloptical path length of no less than 350 mm cannot be adopted as anactual image display device, and thus it is desirable that the opticalsystem is folded as much as possible to be accommodated in a smallspace. So, in FIG. 14 is shown an example in which an optical system ofthe present invention is accommodated in a small space by usingreflecting mirrors M1, M2, M3, M4, and M5. While this optical system isthe seventh embodiment zoom optical system shown in FIG. 9A, it isneedless to say that even with respect to the eighth embodiment zoomoptical system, such configuration can be adopted. It is to be notedthat while with respect to each of the reflecting mirrors M1-M5, thereare two ones, each for the right or left eye, only one of the two isillustrated here for the sake of simplicity because the two exist in thesame position but are displaced in the direction perpendicular to theplane of the drawing.

The reason that the optical system is, as shown in FIG. 14, folded to beaccommodated in a small space is that it was required that the opticalsystem is housed in box 11 as shown in FIG. 15. As described earlier, ifliquid crystal display devices having a low resolution are utilized inan embodiment of the present invention, the liquid crystal displaydevices are to be recognized by the eye in the case of a movie theaterclass screen, and the sense of reality will be lost. Thus, when an imagequality equal to or higher than that of a projector is to be obtained,it is indispensable to introduce the technology in which, as shown inFIG. 16, three liquid crystal display devices (OBJG, OBJR, OBJB), eachprepared for each of the colors of GRB, having a dot resolution matrixof 1980 by 1024 or more (1980 by 760 matrix adapted to 19:9 is alsoavailable), called SXGA, are respectively and separately illuminated bythe green illumination system LSG, the red illumination system LSR, andthe blue illumination system LSB; and three color images, each of whichcorresponds to each color, are separately formed and then combinedtogether to triple the resolution. In addition, when a wide field ofview angle image is to be obtained, heavy and complicated system isnecessarily to be introduced, also from the optics standpoint. If thoserequirements are prioritized, both the size and the weight of theresultant image display device necessarily become impermissible for aneyeglass type display or a head mount type display.

Therefore, in the embodiments of the present invention, a floorstandingtype display having a wide field of view angle, as shown in FIG. 23, isadopted. Fixing the display on a chair or on a bed may also bepermissible; however, in view of, e.g., being able to readily moving thedisplay at home, this floorstanding type is thought to be mostappropriate. However, with respect to a fixed display, the face positioncannot be changed with ease, and with the face being fixed, one suffersnew fatigue. To address this problem, this mechanism is configured suchthat the display can be moved to a desired position in accordance withthe face position, in a manner that the face is covered with a fitelastic member provided on the optical member and with earphone 120supported by a leaf spring. This mechanism is connectable with, e.g., aDVD, a video player, or TV image output machine 114, and is, as with theconventional projector, also connectable with, e.g., a personal computeror TV game machine 113. Further, it is designed such that by means ofimage combining/converting device 121, the existing content imagesthereof are made free of distortion on the display, and multiple imagescan be simultaneously displayed on the display.

It is configured such that the converted images of this data can bedisplayed by full field of view angle display device 118 that issupported, via supporting portion 115 that is constituted by atelescopic bar that can telescope, by vibration isolation type joint bar116 that has a plurality of joint portions. Here, to the device areattached vibration isolation type joint bar 116 and counterbalanceportion (weight free balancer) 117 for canceling the weight of fullfield of view angle display device 118, and the joint mechanism isdevised so that a human does not feel the weight of the full field ofview angle display device and, further, the device follows the movementof the face.

Basically, a human feels only the inertia force generated when movingvibration isolation type joint bar 116 and full field of view angledisplay device 118, and with this mechanism being adopted, high imagequality and wide field of view angle images can be obtained. FIG. 24shows the case where the mechanism is used by a human lying on a bed;for the mechanism to be available in such condition, it is crucial howto construct the jointing portion of vibration isolation type joint bar116.

In the example shown in FIG. 15, supporting portion 13 supports thegravity center position of full field of view angle display device 11which is indicated as box 11 in the earlier description. Morespecifically, concave portion 12 is provided to full field of view angledisplay device 11, and the gravity center position of full field of viewangle display device 11 is supported, via spherical bearing 13 c, bysupporting portion 13. In FIG. 15, (a) is a perspective view; (b) is anelevational view as viewed from the backside; (c) is a cross sectionalplan view; (d) is a side view. Because spherical bearing 13 c is used,full field of view angle display device 11 is, as shown in FIG. 15(a),movable around supporting portion 13. Further, supporting portion 13 hasa telescope structure constituted by member 13 a and member 13 b and is,as shown in FIG. 15(b), movable in the up and down directions. Stillfurther, within the range of concave portion 12, full field of viewangle display device 11 is, as shown in FIG. 15(c), rotationally movablein the right and left directions in the right and left directions and isalso, as shown in FIG. 15(d), rotationally movable in the back and forthdirections.

In other words, because spherical bearing (universal joint) 13 c isused, a structure is realized in which in whatever way the face moves,there are degrees of freedom with respect to the Θx-, Θy-, and Θzdrives. In particular, as shown in FIG. 15(d), the rotational movementwithin the angle range required when the head is moved in the back andforth directions, especially when the user looks down, is guaranteed.

FIG. 16 shows an example in which the folded optical system of FIG. 14is accommodated in the full field of view angle display device 11 shownin FIG. 15. In this example, the sixth embodiment eyepiece opticalsystem shown in FIG. 8A and the seventh embodiment zoom optical systemshown in FIG. 9A are used. In this example, supporting portion 13 ofvibration isolation type joint bar 116 is located at the gravity centerposition of full field of view angle display device 11, moves betweenthe optical systems of both eyes E, and does not interfere with theoptical systems. In this regard, the gravity center position ispreferably set as near as possible to the eyepiece optical system. Thisis because with the gravity center position being set as near aspossible to the position of human head HE, the inertia generated whenfull field of view angle display device 11 is moved in accordance withthe rotational face movement of which rotation center is head HE becomessmaller, resulting in smooth tracking motions.

However, since it is impossible to completely remove the inertia, afixing belt or the like for moving full field of view angle displaydevice 11, with the device and the face being made in close contact witheach other, may be additionally used, if necessary.

In the present invention, as a measure for setting the gravity centerposition as near as possible to the position of the human head, becauseearphone 120 and the eyepiece optical system are heavy, by setting thegravity center position in the vicinity of the eyepiece optical systemas much as possible by devising the layout of the optical system, and byplacing heavy components such as the light emitting liquid crystalportions and electrical systems in the 180-degree opposite direction,with the gravity center being the rotation center, relative to theearphone and the eyepiece optical system, the gravity center issuccessfully located, as shown in FIG. 16, at the position near to thehead without providing a new weight. Additionally, in FIG. 16, it isconfigured such that by providing nose-pad portion 11 a, positioning offull field of view angle display device 11 is performed. Further, 13′shown in FIG. 16 indicates the position of supporting portion 13 whenthe user is lying.

FIG. 17A shows another embodiment example of the present invention.Because the optical systems for both eyes are plane-symmetrical witheach other with respect to the plane that includes axis y dividing thehuman face into the right and left sides and is perpendicular to theplane of the drawing, only the optical system for the left eye will bedescribed here. The light beams having passed through two-dimensionalliquid crystal device 203 are directed to eyeball 209 by the opticalsystem including color beam multiplexing prism 204 and relaymagnification optical system 205; further, in the optical system shownin FIG. 17A, with the light beams being deflected by the four mirrors(213, 216, 217, 221) during the traveling process of the beams, left eyeimage display device 215L and right eye image display device 215R, eachhaving the shape as illustrated, are formed. Note that FIG. 17B is adrawing for showing the layout of mirrors 217 and 221 of the presentoptical system. Mirrors 217 and 221 are, as shown in FIG. 17A, fordeflecting the light beams in the up and down directions and are usedfor making inertia forces other than torques as small as possible bysetting gravity center position GRA of this image display device to benear to rotational movement center CNT of the head. In addition, it isconfigured such that left eye image display device 215L and right eyeimage display device 215R can be moved in the right and left directionsby eye-width adjusting mechanism 214.

More specifically, with respect to the device, like this invention, thatprojects independent screen images to both eyes by means of eyepiecelenses, distortions occurring on the right side and the left side can bemade to follow the same condition by making the optical centers of theeyepiece lenses coincide with the eye centers, and thus, the sense ofdiscomfort and the eyestrain caused when viewing different images withboth eyes can be completely removed. However, because the eye-width, thedistance between human both eyes, differs in individuals, ranging fromabout 5.5 cm to 7.5 cm, the device structure is configured such that inaccordance with the observer's eye-width, the distance between thecenter positions of the light beams incident in the eyes from left eyeimage display device 215L and right eye image display device 215R can bechanged by eye-width adjusting mechanism 214. That is, eye-widthadjusting mechanism 214 has a function of being able to change each ofthe center position of the light beam incident in the left eye from lefteye image display device 215L and the center position of the light beamincident in the right eye from right eye image display device 215R,independently of each other, by changing the positions of mirrors 213.

Image display device 215 is provided with sandwiching members 219functioning as a fixing mechanism that sandwiches ears 218 and also asthe earphones for viewing and hearing, and it is designed such that withthe face being sandwiched with a predetermined force by elastic members220, the face and image display device 215 are mutually fixed.

Also, between eyeballs 209 and eyepiece optical system 208 is providedelastic cover 212 for shielding leakage light from the outside and alsofor preventing eyeballs 209 from coming in contact with eyepiece opticalsystem 208, and the cover not only enhances the sense of realism andabsorption, but also functions as a safety mechanism for preventing theeyes from being hurt.

Next, the role of the above-described four mirrors (213, 216, 217, 221)will be explained. While the four mirrors (213, 216, 217, 221) fold theoptical system to be accommodated in a small space, they serve animportant purpose as well.

In FIG. 17A, both of the cross section of the head 211 and the crosssection of the neck 210 are illustrated; in FIG. 17B, the side viewposture of the present image display device relative to the face whenthe device is in use is illustrated. Since the movement of the head isconducted by the neck 210, it can be assumed that the rotationalmovement center of the head 211 exist within the cross section plane ofthe neck 210. Assuming tentatively that the rotational movement centeris CNT, image display device 215 moves around CNT because the device isfixed to the head 211.

Because the image display device has an layout in which, as shown inFIGS. 17A and 17B, by means of the four mirrors, the device isbilaterally symmetrically constructed and in which also in the verticaldirection, the weight allotment is taken account of, the gravity centerposition is in the vicinity of the rotational movement center CNT of thehead. Accordingly, the neck and the head can be moved with ease.

FIG. 18 shows a part of an optical system embodiment of the presentinvention. This embodiment is configured such that as the opticaldevices for forming images, reflection type liquid crystal devices areused; by dividing a light from one light source being into anS-polarized light and a P-polarized light and by using each polarizedlight for either one of the right and left eyes, the reflection typeliquid crystal devices can be illuminated without loss of light; and thereflected light can be transmitted to the subsequent relay opticalsystems.

First, substrate 301 provided with holes at intervals of 2.5 mm istwo-dimensionally lined with the white light LEDs 302 in accordance withthe panel shape (when the panel ratio is 16:9, in the form of 19:9ratio; when the panel ratio is 4:3, in the form of 4:3 ratio), and theLEDs are wired for simultaneous lighting thereof. Here, because LEDs 302are easily affected by heat, it is devised that a predetermined airspaceis provided or an exhaust heat space is inserted, so that their lifedoes not shorten due to mutual heating. The white light beams emittedfrom LEDs 302 are separated into P-polarized light and S-polarized lightby polarization beam splitter 303, and it is arranged such that theP-polarized light beams enter rod 304L1 and the S-polarized light beamsenter rod 304R1. While the cross sections of the rods 304L1 and 304R1have a shape geometrically similar to the panel shape, they are formedby a glass glass material, plastic glass material, or a member of whichcross section is rectangle-shaped and of which four inner surfaces areconstituted by two paired, facing mirror surfaces, and the rods have astructure by which after the light beams experience a plurality of innersurface reflections, a uniform illumination can be obtained.

Lenses 306L1 and deflection mirror 305L1 are each arranged so that theexit plane of rod 304L1 and the entrance plane of the subsequent rod304L2 are conjugate with each other and so that the light beams can bedeflected. Generally, with respect to a rod, its light uniformizingeffect increases in proportion to the rod's length; and thus, by makingthe total rod lengths of the optical systems for the right and left eyessubstantially equal to each other, the uniformities thereof can besubstantially equivalent to each other. In a state that the uniformityhas been further increased by the subsequent rod 304L2, it is furtherarranged by deflection mirrors 305L2, 307L, 305R1, 307R and by lenses306L2 and 306R1 such that the exit planes of the above-described rods304L2 and 304R1 are conjugate with the surfaces of each panels 310L(r),310L(g), 310L(b), 310R(r), 310R(g), and 310R(b), each constituted by areflection type liquid crystal device, and thus a uniform illuminationis performed. Here, the white arrows indicate the direction where relayoptical systems described later are located. Here, because each of thelight beams is originally either P-polarized light or S-polarized light,they are adjusted so that they are deflected by the predeterminedpolarization beam splitter 307L or 307R.

Because the operations of this optical system are the same for each ofthe right and left subsystems thereof, the following description will bemade for the left eye subsystem. Note that in the figure, the referencesymbol L is attached to the constituent elements for the left eye useand the reference symbol R is attached to the constituent elements forthe right eye use, to distinguish therefrom.

The light from LEDs 302 is separated into P-polarized light andS-polarized light by polarization beam splitter 303. The followingdescription will be made assuming that the P-polarized light, among thetwo, is used for the left eye use; however, even if it is assumed thatthe S-polarized light is used for the left eye use, theoperation/working-effect remains the same. The separated light(P-polarized light) is, as described above, uniformized via rods 304L1and 304L2, is reflected by polarization beam splitter 307L viadeflection mirror 305L2 and lens 306L2, is incident in RGB light beamdivision multiplexer prism 309L via lens 306L2 and λ/4 plate 308L, andis separated into red light, green light, and blue light.

The separated red light, green light, and blue light respectivelyilluminate each of the panels 310L(r), 310L(g), and 310L(b), andbecause, as described above, the exit plane of rod 304L2 is madeconjugate with the surfaces of each panels 310L(r), 310L(g), and310L(b), the surface of each panel is uniformly illuminated.

On each panel is formed a reflecting pattern corresponding to eachcolor; the reflected lights are combined into a single beam, with thelights passing through RGB light beam division multiplexer prism 309L;and the combined beam is incident in polarization beam splitter 307L viaλ/4 plate 308L and lens 306L2. Because, in this process, with the beampassing through λ/4 plate 308L twice, the beam has been converted intoS-polarized light, the beam this time transmits through polarizationbeam splitter 307L and is lead to the relay optical system that islocated in the direction of the arrow.

If a half mirror or a half prism is used instead of polarization beamsplitter 307L, about a half amount of light is lost upon the reflectionand the transmission, and thus only a fourth of the original lightamount is available; in contrast, in this embodiment, with polarizationbeam splitter 307L and λ/4 plate 308L being used in combination,substantially the whole amount of light can be effectively used.

In addition, by making the patterns formed on each of panels 310L(r),310L(g), 310L(b), 310R(r), 310R(g), and 310R(b) different from eachother, different images can be sent to each eye to providethree-dimensional image information, and the light amounts reachingright and left eyes can also be adjusted.

It is to be noted that in this embodiment, polarization beam splitter307L is assumed to reflect P-polarized light and transmit S-polarizedlight, and, on the other hand, polarization beam splitter 307R isassumed to reflect S-polarized light and transmit P-polarized light, butby providing a λ/2 plate, which converts P-polarized light intoS-polarized light, and vice versa, in front of either one ofpolarization beam splitter 307L and polarization beam splitter 307R,polarization beam splitters having the same characteristics can be usedas polarization beam splitter 307L and polarization beam splitter 307R.

Next, FIG. 19 shows a modification example of the optical system shownin FIG. 18. In this figure, because the optical system subsequent topolarization beam splitter 303 is the same as the optical system shownin FIG. 18, the same constituent elements as those shown in FIG. 18 aredenoted by the same reference numerals, descriptions thereof will beomitted, and only the optical system arranged before polarization beamsplitter 303 will be described. The above-described white light LEDs 302have a simple optical system and excel in space saving; however, becausetheir color wavelength condition and light intensity depend on theirspecifications, there are many problems in finely adjusting their colorcondition. In the embodiment shown in FIG. 19, to address suchsituation, it is configured such that the LEDs are divided into threegroups, R-LED group 302(r), G-LED group 302(g), and B-LED group 302(b),each light beams are combined by RGB light beam multiplexer prism 309,and thereafter the relay of the beam and a uniform illumination isperformed by rod 304. And, lens 306 that makes the exit plane of rod 304and the incident planes of rods 304L1 and 304R1 conjugate with eachother and defection mirror 305 that changes the beam direction areadditionally arranged. In this mechanism, because the light intensity ofeach LED group can be adjusted through voltage adjustment as required,the color adjustment of the images can be easily performed, and with anycombination of color LEDs being available, still better images can beobtained.

FIG. 20 shows an example of the optical system arranged subsequent tothe optical systems shown in FIGS. 18 and 19. Because the optical systemshown in FIG. 20 is an optical system that is basically the same as theoptical system shown in FIG. 17A, the same constituent elements as thoseshown in FIG. 17A are denoted by the same reference numerals, anddescriptions thereof will be omitted; in contrast to the optical systemof FIG. 17A, the optical path is not folded, and thus the deflectionmirrors shown in FIG. 17A are not used. Note that in FIG. 20, 222L and222R denote image planes, and on those planes are projected and imagedthe images formed on the panels 310L(r), 310R(r), 310L(g), 310R(g),310L(b), and 310R(b) of FIGS. 18 and 19.

FIG. 20 shows an example of an optical system which projects combinedimages from two two-dimensionally light emitting type photoelectricdevices (reflection type liquid crystal devices) on the right and lefteyes. 401 denotes a light source device; in this are housed, e.g., thewhite light LEDs 302 and polarization beam splitter 303 of FIG. 18; theseparated P-polarized light and S-polarized light respectively enter thetwo rods 402. One optical system and the other optical system aresubstantially equivalent to each other; and thus, in the followingdescription, the corresponding constituent elements will be denoted bythe same reference numerals, the description will be made only on oneoptical path (the one proceeding upwardly from light source device 401),and the different portions relative to the right and left eyes will bedescribed as occasion arises.

The light having exited from rod 402 is deflected by deflection prism403; after passing through rod 404, the traveling direction of the lightbeam is reversed by the two deflection prisms 405 and 406; after passingthrough rod 407, the light beam is deflected by deflection prism 409, isreflected by polarization beam splitter 410, and enters image formingportion 411. Image forming portion 411 is constituted by opticalelements, such as 308L, 309L, 310L(r), 310L(g), and 310L(r) of FIG. 18,and reflects the incident light in accordance with the patterns on thereflection type liquid crystal devices. The reflected light passesthrough polarization beam splitter 410, and is made to have anappropriate magnification by zoom optical system 412.

On the other hand, the optical path of the light having exited from thezoom optical system 412 located on the other optical path is folded bydeflection prism 413. The light having exited from the zoom opticalsystem located on the one optical path travels straight, enters halfprism 414 together with the former light, and is combined with the lightbeam having traveled along the other optical path; of the combined lightbeams, the one for the left eye passes through deflection prism 415 andoptical path length adjusting mechanism 416, is projected on screen 417,and is projected on the left eye via eyepiece optical system 418. On theother hand, of the combined light beams, the one for the right eye isprojected on screen 417 via deflection prisms 419 and 420 and isprojected on the right eye via eyepiece optical system 418.

When compared with the optical system shown in FIGS. 13C and 13D, theoptical system ranging from zoom optical systems 412 to screens 417differs in that the deflection prisms' positions differ from those ofthe optical system shown in FIGS. 13C and 13D, in that the reflectiontype liquid crystal devices are used instead of the transmission typeliquid crystal devices, and in that the image planes thereof are theobject planes of zoom optical systems 412. However, other aspects ofthis embodiment are essentially the same as the optical system shown inFIGS. 13C and 13D; and because the eyepiece optical systems are the sameas those described with reference to, e.g., FIG. 1A, descriptionsthereof will be omitted.

Additionally, the variable magnification ratio of zoom optical systems412 should preferably be set not to be too large. More specifically,with respect to the zoom optical system, the aberrations are required tobe made small with respect to both of the maximum magnification stateand the minimum magnification state, and, for this reason, when thevariable magnification ratio is set to be large, the numerical aperture(NA) is required to be set to be small. When the numerical aperture issmall, the roughness of screen 417 becomes highly visible when the imageis projected on the screen. Because the roughness of the screen becomesless visible when the numerical aperture is large, it is preferable thatthe variable magnification ratio of zoom optical systems 412 be madesmaller and, up to the amount corresponding to the smallermagnification, the numerical aperture be made larger. This applies incommon to the zoom optical systems of all of the optical systemsdescribed hereinbefore.

FIG. 22 shows an outline of an optical system for projecting images fromtwo-dimensionally light emitting type photoelectric devices (reflectiontype liquid crystal devices), each provided for the right and left eyes,onto the right and left eyes, and the optical system has an opticalsystem corresponding to the zoom optical systems and eyepiece opticalsystems shown in FIG. 20. In FIG. 22, the same constituent elements asthose shown in FIG. 21 are denoted by the same reference numerals, anddescriptions thereof will be omitted. In this example, the images formedby the right and left image forming portions 411 are separatelyprojected onto the corresponding right and left eyes. The optical systemis similar to the optical system shown in FIG. 21, except that opticalpath length adjusting mechanisms 416 are respectively provided for theright and left eyes, that deflection prisms 421 are provided, and thatthere is no image combining by means of half prism 414; and thus nodetailed description will be required.

With the optical path folding and reversing optical system shown in FIG.21 or 22 being used, the overall device can be made compact.

As described above, in accordance with the present invention,high-resolution, high-luminance, and high-quality moving pictures havinga large field of view angle comparable to the field of view viewed by ahuman can be provided. Because the better part of the effects of thepresent invention has been described in connection with the descriptionsof the embodiments, still further effects will be described next. First,regarding the eyepiece optical system, because it is configured suchthat conic constant k is made to satisfy k<0, i.e., a convex lens havinga hyperboloid, a paraboloid, or an ellipsoid is arranged in the vicinityof the pupil position (crystalline lens), and that a cemented lens isarranged in the vicinity of the screen, high image quality images ofwhich various aberrations, including chromatic aberration, are vastlyimproved can be provided, even in the case of wide range images having afield of view angle of ±22.5 degrees or more. Here, when conic constantk is made to satisfy k<0, the resultant surface may be thought to be ahyperboloid, a paraboloid, or an ellipsoid; however, the asphericsurface is generally a rotationally symmetric quadratic surface, and thecurved surface Z(r) of the rotationally symmetric quadratic surface canbe expressed:${Z(r)} = {\frac{c \cdot r^{2}}{1 + \sqrt{\left\{ {1 - {\left( {1 + k} \right) \cdot c^{2} \cdot r^{2}}} \right.}} + {A \cdot r^{2}} + {B \cdot r^{2}} + {C \cdot r^{8}} + {D \cdot r^{10}} + {{E \cdot r^{12}}{F \cdot r^{14}}} + {G \cdot r^{14}} + {H \cdot r^{18}} + {J \cdot r^{20}}}$where c is a constant representing a curvature; r²=x²+y²; and A, B, C,D, E, and F are aspheric surface coefficients (of even orders). kdenotes the conic constant, satisfying k<0. Thus, a lens surfaceincorporating the discretionary constants, A, B, C, D, E, and F can alsobe conceived. In the present invention, rotationally symmetric quadraticsurfaces using those formulas are also included.

Further, the above-described combination sufficiently meets the timewhen the eyes conduct the action to look around to widen the field ofview and can also provide sharp images. This is an important action foravoiding the “fatigue” felt when the human eyes continually conduct oneaction and the function of the eyes gradually cannot exercise theoriginal function, and the embodiments of the present invention thatprovide a field of view during the “look-around” avoiding action play animportant role for not feeling the “fatigue.”

Next, regarding the zoom mechanism, the mechanism also plays a role inalleviating VE sickness. Normal contents are not assumed to be outputtedas wide field of view angle images; and thus the video camera for takingimages is not positioned at a fixed position, and, for the purpose ofenhancing the image effect, images are often taken with the camera beingdirected to various directions, or zoom operations are often overused.In the case of a display comparable to the usual television image of 10to 50 inches, there arises no problem; however, in the case of an imagescreen of 60 degrees or more (comparable to 100 inches), the symptom of“self-motion perception: ‘An illusion felt as if oneself were moving’ iscreated, and the equilibrium sense is affected. A moving image thatgives information to a wide range field of view affects the equilibriumsense, and the mismatch between the visual information brought by theimage and the somatosensory information may cause discomfort or motionsickness)” may be induced. That said, a landscape taken by a fixedcamera and an infinite distance wide range field of view image of 60degrees or more (comparable to 100 inches) are images akin to reality,are full of realism, and give a natural stereoscopic appearance withoutparallax, which brings about significant effects of relaxation andremedying eyestrain.

Therefore, with the image display device being adjusted, by using a zoommechanism, depending not only on the resolution of the content but alsoon the kind of the content image, comfortable image information can beobtained. For that purpose, the zoom mechanism preferably has a zoomrange of over about two times that covers the range ranging from aninfinite distance wide range field of view image of 60 degrees or more(comparable to 100 inches) which is likely to create self-motionperception to an image of 30 degrees or less (comparable to 50 inches)which is not likely to create self-motion perception.

Further, contents of existing DVD, video, BS images, etc. have theirrespective predetermined field angles, and thus the image screen sizescorresponding to their image qualities, instead of a wide field of view,are desirable. More specifically, if the field angle is enlargedblindly, then the coarseness of pixels is recognized by the eyes, andthe degree of the disadvantage that one feels uneasy as to the poornessof image quality becomes larger than the degree of advantage that alarge-sized image screen can be obtained. Thus, in this embodiment, itis designed that the most appropriate field angles for those contentsare set by using the zoom mechanism to always obtain high imagequalities. In consideration of the image dot sizes, a zoom mechanism ofabout 4 to 5 times, i.e., ±18 to +60 degrees in terms of field of viewangle, is preferably provided.

In addition, the embodiments of the present invention can provide allkinds of structures, for example, a structure in which theabove-described display device is disposed to at least one of the rightand left eyeballs, and a structure in which the above-described displaydevices are respectively disposed to each of the right and left eyeballsand the positions of the devices are adjusted in accordance with thedistance between the eyeballs; and thus wide-ranging applicationsadapted for particular uses can be conceived. This means, without beinglimited to the functions of the above-described optical system shift inaccordance with the eye-width and zoom mechanism, that by configuringsuch that a part or the whole of the respective eyepiece optical systemsexisting between the human eyes and the screens can be separately movedin the focus direction, all of myopic persons, hyperopic persons, andastigmatic persons can observe good infinite distance images withoutwearing eyeglasses or contact lenses. Further, because by shortening therelative distance between the screens and the eyepiece optical systems,a condition, adapted to image contents, in which nearby objects areobserved, can be realized, still more enhanced sense of realism can beobtained. In this case, screen G is only required to be provided with adrive mechanism that gives a driving force in the optical axisdirection, and the zoom optical system is only required to be providedwith a focusing mechanism that varies the focus position in response tothe distance between the liquid crystal display device and screen G onwhich images are projected.

Still further, as the above-described photoelectric devices,two-dimensionally light emitting type liquid crystal display deviceswhich are perpendicular to the light beams are adopted, and thus, imageinformation comparable to the real field of view can be provided with afine resolution and low power consumption. Regarding the light emittingportion, high intensity LEDs or cold cathode tubes are used, whichbrings about significant effect in the aspect of low power consumption,life, and size. In addition, by using optical fibers, ahigh-illuminance, uniform illumination is realized with a small space;and, while red, green, and blue light sources have originallydifferences with respect to illuminance, light emitting direction, etc.,the use of the optical fibers also brings about significant effect inadjusting the different light sources to produce the same resultantilluminance.

However, when the light amounts outputted from the two-dimensionallylight emitting type liquid crystal display devices are fixed, therearises a possibility that an illuminance difference between two imagesdue to the magnification difference occurs when the two images arecombined by the zoom optical systems and the half mirror. To addressthis difficulty, in the present invention, it is configured such that byvarying the current values given to the above-described light sources inaccordance with the magnification difference when the images arecombined, the illuminance of the above-described high intensity LEDs orcold cathode tubes themselves is controlled in accordance with themagnification change so that a large illuminance difference within thecombined image does not occur. However, the varying of illuminance byvarying the current intensities causes a thermal distribution change;the emission wavelengths themselves change; and there arises apossibility that the color balance cannot be adjusted. Thus, instead ofvarying the current values given to the light sources associated witheach images to be combined, the light sources are made sufficientlybright, and with aperture stop STO being arranged in the vicinity of thepupil plane of the zoom optical system, the illuminance of each image iscontrolled so that the light amount is adjusted in accordance with themagnification change. Further, when the light amount is sufficientlysecured, it may be configured such that by combining two polarizationplates and by varying the rotation angles thereof, the light is adjustedin accordance with the magnification change; however, because threecolor multiplexer 162 has respective polarization characteristics foreach color, it is preferable that by using, e.g., a λ/4 plate, thepolarization characteristics are removed in advance.

Further, by virtue of the above-described configuration, the full fieldof view angle display device 118 of FIG. 23 does not itself consume alarge amount of power. Thus, the connection system attached with BS/CS110° antenna I/O ports, phone line ports, VHF/UHF antenna I/O ports,audio I/O ports, image I/O ports, S-image I/O ports, D (D1/D2/D3/D4)video I/O ports, optical digital audio output ports, i. LINK ports,analog RGB I/O ports, and DC input ports, all for taking outsideinformation, is entirely separated from the very full field of viewangle display device 118 and is attached to image combining/convertingdevice 121. And, it is configured such that all inputted data via theabove-described ports from outside information devices of, e.g., a DVD,a television, or a computer are converted to infrared light data; theconverted data are sent from an infrared light transmitting portion andare received by the infrared light receiving portion of theabove-described full field of view angle display device 118; and, afterthe received data being converted to image and audio data, imageinformation is provided on the display. Further, regarding the powersupply to full field of view angle display device 118, it is configuredsuch that a battery is incorporated in the device and that when thedevice is not used, the battery is charged via vibration isolation typejoint bar 116; and thus, there is no fixed line portion in full field ofview angle display device 118. Thus, it may also be configured such thatthe device is detached from the main body and then carried to any placewhere a plurality of full field of view angle display device supportingmechanisms 170 are set.

As described above, in accordance with the present invention,high-quality wide range image images can be taken as image information;and by conceiving, by using this fact, various combinations, full-scaleinformation input-output devices that are superior to wearable displaysand wearable computers can prospectively be provided. Moreover, newsense game softwares, wide range image DVDs, and wide range image videotapes, efficiently utilizing the wide range image images, canprospectively be sold, and, further, full-scale virtual reality systemcan prospectively be provided.

The image display device according to the present invention can ofcourse be implemented as a eyeglass type display or as a head mount typedisplay; but, with the image display device being directly positioned ona chair in a movie theater or airplane, on a chair for relaxation, or ona bed for nursing a bedridden elderly person, the device can be providedas a mechanism that has dissolved the problem of discomfort due to theweight or wearing of the device. In particular, the marketability of thedevice is also high in that provision of images full of reality to asick person or bedridden elderly person whose moreover is restrictedbrings about a significant relaxation effect and can give vigor forrecovering from illness or vigor for living.

To summarize the above content, the following merchantabilities can beexpected in utilizing the present invention.

Large screen personal computers and CADs that do not make one feel theweight and fatigue, large screen displays that substitute movie theatersand projectors, provision of 3D large screen images full of reality, theInternet reception of images from the above-described video mechanism,provision of images full of reality to a sick person or bedriddenelderly person, relaxation image display devices, provision of new senseTV game images, provision of large screen images in a small space, highconfidentiality information display systems for individual use, virtualreality displays, remote controllable large screen displays, digitalnewspaper reception systems with a wide screen, relaxation service inthe first-class section of an airplane, etc., educational materials thatdo not injure the eyesight, new display games in an amusement facility,etc. can be conceived.

1. An image display device that projects, via a relay optical system,the light emitted from a first two-dimensionally light emitting typephotoelectric device which is perpendicular to the light beam emittingdirection onto first and second light diffusing bodies which areindependent of each other relative to the right and left eyes andprojects and images the transmitted images of said light diffusingbodies, via first and second eyepiece optical systems which respectivelycorrespond to the first and second light diffusing bodies, onto theretina in the eyeball, with the imaged transmitted images being a widerange image having a field of view angle of ±22.5 degrees or more, saidimage display device being characterized in that the center distancebetween said first and second light diffusing bodies is within 5.5 to7.5 cm, in that said first and second eyepiece optical systems are eachconstituted by at least two lenses composed of, sequentially from theeyeball's crystalline lens side, one or more convex lens(es) and acemented lens, in that at least one surface of the lens surfaces of saidconvex lens(es) is a conic surface with conic constant K<0, in that thecemented portion of said cemented lens is made a convex surface on theside of said light diffusing body, and in that the color dispersion ofthe light diffusing body side lens of said cemented lens is made largerthan that of the other lens thereof.
 2. An image display device thatprojects, via a relay optical system, the light emitted from a firsttwo-dimensionally light emitting type photoelectric device which isperpendicular to the light beam emitting direction onto first and secondlight diffusing bodies which are independent of each other relative tothe right and left eyes and projects and images the transmitted imagesof said light diffusing bodies, via first and second eyepiece opticalsystems which respectively correspond to the first and second lightdiffusing bodies, onto the retina in the eyeball, with the imagedtransmitted images being a wide range image having a field of view angleof ±22.5 degrees or more, said image display device being characterizedin that the center distance between said first and second lightdiffusing bodies is within 5.5 to 7.5 cm, in that said first and secondeyepiece optical systems are each constituted by at least two lensescomposed of, sequentially from the eyeball's crystalline lens side, oneor more convex lens(es) and a cemented lens, in that at least onesurface of the lens surfaces of said convex lens(es) is a conic surfacewith conic constant K<0, in that the cemented portion of said cementedlens is made a concave surface on the side of said light diffusing body,and in that the color dispersion of the light diffusing body side lensof said cemented lens is made smaller than that of the other lensthereof.
 3. An image display device that projects, via a relay opticalsystem, the light emitted from a first two-dimensionally light emittingtype photoelectric device which is perpendicular to the light beamemitting direction onto first and second light diffusing bodies whichare independent of each other relative to the right and left eyes andprojects and images the transmitted images of said light diffusingbodies, via first and second eyepiece optical systems which respectivelycorrespond to the first and second light diffusing bodies, onto theretina in the eyeball, with the imaged transmitted images being a widerange image having a field of view angle of ±22.5 degrees or more, saidimage display device being characterized in that the center distancebetween said first and second light diffusing bodies is within 5.5 to7.5 cm, in that said first and second eyepiece optical systems are eachconstituted by at least two lenses composed of, sequentially from theeyeball's crystalline lens side, one or more convex lens(es) and acemented lens, in that at least one surface of the lens surfaces of saidconvex lens(es) is a conic surface with conic constant K<0, in that saidcemented lens has at least two cemented portions, in that the cementedsurface located near to said light diffusing body is made a concavesurface on the side of said light diffusing body, in that the othercemented surface is made a convex surface on the side of said lightdiffusing body, and in that the color dispersion of the center lensbounded by said cemented portions is made larger than those of the othertwo lenses surrounding the center lens.
 4. An image display device thatprojects, via a relay optical system, the light emitted from a firsttwo-dimensionally light emitting type photoelectric device which isperpendicular to the light beam emitting direction onto first and secondlight diffusing bodies which are independent of each other relative tothe right and left eyes and projects and images the transmitted imagesof said light diffusing bodies, via first and second eyepiece opticalsystems which respectively correspond to the first and second lightdiffusing bodies, onto the retina in the eyeball, with the imagedtransmitted images being a wide range image having a field of view angleof ±22.5 degrees or more, said image display device being characterizedin that the center distance between said first and second lightdiffusing bodies is within 5.5 to 7.5 cm, in that said first and secondeyepiece optical systems are each constituted by at least two lensescomposed of, sequentially from the eyeball's crystalline lens side, oneor more convex lens(es) and a cemented lens, in that at least onesurface of the lens surfaces of said convex lens(es) is a conic surfacewith conic constant K<0, in that said cemented lens has at least twocemented portions, in that the cemented surface located near to saidlight diffusing body is made a convex surface on the side of said lightdiffusing body, in that the other cemented surface is made a concavesurface on the side of said light diffusing body, and in that the colordispersion of the center lens bounded by said cemented portions is madesmaller than those of the other two lenses surrounding the center lens.5. An image display device according to claim 1, characterized in thatat least one surface of the lens surfaces of said convex lens(es) is aconic surface with conic constant K<−1.
 6. An image display device thatprojects, via a relay optical system, the light emitted from a firsttwo-dimensionally light emitting type photoelectric device which isperpendicular to the light beam emitting direction onto first and secondlight diffusing bodies which are independent of each other relative tothe right and left eyes and projects and images the transmitted imagesof said light diffusing bodies, via first and second eyepiece opticalsystems which respectively correspond to the first and second lightdiffusing bodies, onto the retina in the eyeball, with the imagedtransmitted images being a wide range image having a field of view angleof ±22.5 degrees or more, said image display device being characterizedin that the center distance between said first and second lightdiffusing bodies is within 5.5 to 7.5 cm, in that said first and secondeyepiece optical systems are each constituted by at least two lensescomposed of, sequentially from the eyeball's crystalline lens side, oneor more convex lens(es) and a cemented lens, in that the cementedportion of said cemented lens is made a convex surface on the side ofsaid light diffusing body, in that the color dispersion of the lightdiffusing body side lens of said cemented lens is made larger than thatof the other lens thereof, and in that said light diffusing body is madea curved surface having a concave surface shape toward said cementedlens.
 7. An image display device that projects, via a relay opticalsystem, the light emitted from a first two-dimensionally light emittingtype photoelectric device which is perpendicular to the light beamemitting direction onto first and second light diffusing bodies whichare independent of each other relative to the right and left eyes andprojects and images the transmitted images of said light diffusingbodies, via first and second eyepiece optical systems which respectivelycorrespond to the first and second light diffusing bodies, onto theretina in the eyeball, with the imaged transmitted images being a widerange image having a field of view angle of ±22.5 degrees or more, saidimage display device being characterized in that the center distancebetween said first and second light diffusing bodies is within 5.5 to7.5 cm, in that said first and second eyepiece optical systems are eachconstituted by at least two lenses composed of, sequentially from theeyeball's crystalline lens side, one or more convex lens(es) and acemented lens, in that the cemented portion of said cemented lens ismade a concave surface on the side of said light diffusing body, in thatthe color dispersion of the light diffusing body side lens of saidcemented lens is made smaller than that of the other lens thereof, andin that said light diffusing body is made a curved surface having aconcave surface shape toward said cemented lens.
 8. An image displaydevice according to claim 6, characterized in that at least one surfaceof the lens surfaces of said convex lens(es) is a conic surface withconic constant K<0.
 9. An image display device according to claim 8,characterized in that at least one surface of the lens surfaces of saidconvex lens(es) is a conic surface with conic constant K<−1.
 10. Animage display device according to claim 2, characterized in that thedistance between the optical centers of said first and second eyepieceoptical systems and the distance between the centers of the projectedimages on said first and second light diffusing bodies are madeadjustable so that those two distances are equal to the eye-width. 11.An image display device according to claim 1, characterized in that saidrelay optical system makes the projection magnification of the image ofsaid first photoelectric device projected onto said light diffusingbodies variable, in that said relay optical system is a non-telecentricsystem in which the principal ray of each light beam incident on saidlight diffusing bodies changes from of a diverging direction type to ofa converging direction type when the projection magnification changesfrom a magnifying magnification to a reducing magnification, and in thatthe principal rays that are emitted from said light diffusing bodies andreach the pupil of said eyeball are inclined toward the convergingdirection when the principal rays are emitted from said light diffusingbodies.
 12. An image display device according to claim 1, characterizedin that said light diffusing bodies that diffuse light are atransmission type diffusing plate constituted by a transmission plate onwhich abrasive grains of a metal oxide or metallic carbide of whichgrain diameter is precisely controlled with micron-grade are coated. 13.An image display device according to claim 12, characterized in thatsaid abrasive grains are made of at least one of silicon carbide,chromium oxide, tin oxide, titanium oxide, magnesium oxide, and aluminumoxide and in that said transmission plate is a polyester film.
 14. Animage display device according to claim 1, characterized in that it hasa second two-dimensionally light emitting type photoelectric device thatis arranged such that the light beams thereof are perpendicular to thoseof said first photoelectric device and also has, in said relay opticalsystem, which projects the light emitted from said first photoelectricdevice onto said light diffusing bodies, a light divider that dividesthe light beams and leads them to said first and second light diffusingbodies, in that the light beams from said second photoelectric deviceare made incident on said light divider such that the light beams areperpendicular to the light beams emitted from said first photoelectricdevice, and in that said light divider has a function to divide thelight from said first photoelectric device from the light from saidsecond photoelectric device and also to combine the divided light beamsof said first photoelectric device with the divided light beams of saidsecond photoelectric device and lead them to said first light diffusingbody and to said second light diffusing body, respectively.
 15. An imagedisplay device according to claim 14, characterized in that thedifference between the number of reflections by mirrors experienced bythe light beams emitted from said first photoelectric device from thefirst reflection by a mirror up to reaching the user's eyes and thenumber of reflections by mirrors experienced by the light beams emittedfrom said second photoelectric device from the first reflection by amirror up to reaching the user's eyes is 0 or an even number.
 16. Animage display device according to claim 14, characterized in that thedifference between the number of reflections by mirrors experienced bythe light beams emitted from said first photoelectric device from thefirst reflection by a mirror up to reaching the user's right eye and thenumber of reflections by mirrors experienced by the light beams emittedfrom said first photoelectric device from the first reflection by amirror up to reaching the user's left eye is 0 or an even number and inthat the difference between the number of reflections by mirrorsexperienced by the light beams emitted from said second photoelectricdevice from the first reflection by a mirror up to reaching the user'sright eye and the number of reflections by mirrors experienced by thelight beams emitted from said second photoelectric device from the firstreflection by a mirror up to reaching the user's left eye is 0 or aneven number.
 17. An image display device according to claim 14,characterized in that the distance between the optical centers of saidfirst and second eyepiece optical systems and the distance between thecenters of the projected images on said first and second light diffusingbodies are made adjustable so that those two distances are equal to theeye-width and in that an optical path length adjusting mechanism thatadjust, when the two distances, the distance between the optical centersof the eyepiece optical systems and the distance between the centers ofthe projected images, are adjusted, the optical path length from saidfirst photoelectric device to the user's eyes and the optical pathlength from said second photoelectric device to the user's eyes so thateach of them does not change is provided.
 18. An image display deviceaccording to claim 14, characterized in that said relay optical system,which projects the light emitted from said first photoelectric deviceonto said light diffusing bodies, makes the projection magnificationrelative to said light diffusing bodies of the light beams projectedonto said light diffusing bodies variable and in that an illuminancevarying mechanism for making, when the magnification is varied, theilluminances of the respective pictures projected from said firstphotoelectric device and said second photoelectric device onto saidlight diffusing bodies substantially equal to each other is provided.19. An image display device according to claim 1, characterized in thatsaid first photoelectric device is a transmission type or reflectiontype liquid crystal device element and has three pieces of liquidcrystal devices, each corresponding to each of the colors of G, B, andR, and an illumination system that illuminates said liquid crystaldevices and in that said illumination system is a uniformizing opticalsystem that uniformizes the outputs from light emitting LEDs of G, B,and R.
 20. An image display device according to claim 19, characterizedin that said uniformizing optical system has, for each of the LEDs of G,B, and R, a plurality of high intensity LEDs, collects the lights fromthose plurality of LED light emitting portions by using optical fibers,and illuminates said liquid crystal device with the collected lights.21. An image display device according to claim 1, characterized in thatsaid first photoelectric device is a transmission type or reflectiontype liquid crystal device element and has three pieces of liquidcrystal devices, each corresponding to each of the colors of G, B, andR, and an illumination system that illuminates said liquid crystaldevices and in that said illumination system is cold cathode tubes of G,B, and R.
 22. An image display device according to claim 21,characterized in that said uniformizing optical system has, for each ofthe colors of G, B, and R, a plurality of cold cathode tubes, collectsthe lights from those plurality of cold cathode tubes by using opticalfibers, and illuminates said liquid crystal device with the collectedlights.
 23. An image display device according to claim 1, characterizedin that at least a portion of said image display device is supported bya portion other than a user, is also in contact with the face of saiduser, and is made movable in response to the movement of the face ofsaid user.
 24. An image display device which has an optical system thathas at least, relative to each of the right and left eyeballs, portionsindependent of each other and which projects an image into each of saidright and left eyeballs, said image display device being characterizedin that said independent portions are each constituted by at least twolenses composed of, sequentially from said eyeball side, one or moreconvex lens(es) and a cemented lens and in that the surface, locateddistant from the eyeball, of the convex lens, among said convex lenses,located nearest to the eye ball is made a conic surface with conicconstant K<0.
 25. An image display device according to claim 24,characterized in that said cemented lens is provided, in the independentportion of said optical system, on the nearest side of an image formingsurface forming said image.
 26. An image display device according toclaim 1, characterized in that it has, instead of the firstphotoelectric device, two two-dimensionally light emitting typephotoelectric devices which are perpendicular to the light beam emittingdirection and in that it is configured such that, instead of projecting,via said relay optical system, the light emitted from said firstphotoelectric device onto said first and second light diffusing bodieswhich are independent of each other relative to the right and left eyes,the lights emitted from said two photoelectric devices are eachprojected, via said relay optical system, onto said first and secondlight diffusing bodies which are independent of each other relative tothe right and left eyes.
 27. An image display device according to claim26, characterized in that the distance between the optical centers ofsaid first and second eyepiece optical systems and the distance betweenthe centers of the projected images on said first and second lightdiffusing bodies are made adjustable so that those two distances areequal to the eye-width and in that an optical path length adjustingmechanism that adjust, when the two distances, the distance between theoptical centers of the eyepiece optical systems and the distance betweenthe centers of the projected images, are adjusted, the optical pathlengths from said two photoelectric device to the user's eyes so thateach of them does not change is provided.
 28. An image display deviceaccording to claim 26, characterized in that said relay optical system,which projects the lights emitted from said two photoelectric devicesonto said light diffusing bodies, makes each of the projectionmagnifications relative to said light diffusing bodies of the lightbeams projected onto said light diffusing bodies variable and in that anilluminance varying mechanism for making, when the magnifications arevaried, the illuminances of the respective pictures projected from saidtwo photoelectric devices onto said light diffusing bodies substantiallyequal to each other is provided.
 29. An image display device thatprojects, via a relay optical system, each of the lights emitted fromtwo two-dimensionally light emitting type photoelectric devices whichare perpendicular to the light beam emitting direction onto first andsecond light diffusing bodies which are independent of each otherrelative to the right and left eyes and projects and images thetransmitted images of said light diffusing bodies, via first and secondeyepiece optical systems which respectively correspond to the first andsecond light diffusing bodies, onto the retina in the eyeball, with theimaged transmitted images being a wide range image having a field ofview angle of ±22.5 degrees or more, said image display device beingcharacterized in that said two two-dimensionally light emitting typephotoelectric devices are each a reflection type liquid crystal deviceelement, in that one light source, a first polarization beam splitterthat divides the light emitted from said light source into P-polarizedlight and S-polarized light, and an optical system that leads each ofthe divided P-polarized light and S-polarized light respectively to saidtwo two-dimensionally light emitting type photoelectric devices, thusilluminates said two two-dimensionally light emitting type photoelectricdevices, and leads the lights reflected thereby to said relay opticalsystem are provided, and in that said optical system leads the reflectedlights to said relay optical system via second polarization beamsplitter, the reflected lights being the P-polarized lights convertedfrom the S-polarized lights, or being the S-polarized lights convertedfrom the P-polarized lights.
 30. An image display device that projects,via a relay optical system, each of the lights emitted from two sets oftwo-dimensionally light emitting type photoelectric devices which areperpendicular to the light beam emitting direction onto first and secondlight diffusing bodies which are independent of each other relative tothe right and left eyes and projects and images the transmitted imagesof said light diffusing bodies, via first and second eyepiece opticalsystems which respectively correspond to the first and second lightdiffusing bodies, onto the retina in the eyeball, with the imagedtransmitted images being a wide range image having a field of view angleof ±22.5 degrees or more, said image display device being characterizedin that said two sets of two-dimensionally light emitting typephotoelectric devices are each constituted by three reflection typeliquid crystal device elements, each corresponding to each of the colorsof G, B, and R, in that one light source, a first polarization beamsplitter that divides the light emitted from said light source intoP-polarized light and S-polarized light, and an optical system thatleads each of the divided P-polarized light and S-polarized lightrespectively to said two sets of two-dimensionally light emitting typephotoelectric devices, thus illuminates said two two-dimensionally lightemitting type photoelectric devices, and leads the lights reflectedthereby to said relay optical system are provided, and in that saidoptical system leads said P-polarized light or S-polarized light to saidtwo-dimensionally light emitting type photoelectric devices, whichaccommodate the colors of G, B, and R, via a second polarization beamsplitter, a and an RGB light beam division multiplexer prism and leadsthe reflected lights to said relay optical system via said RGB lightbeam dividing/multiplexing prism, and said second polarization beamsplitter, the reflected lights being the P-polarized lights convertedfrom the S-polarized lights, or being the S-polarized lights convertedfrom the P-polarized lights.
 31. An image display device according toclaim 29, wherein said light source is a plurality of white light LEDstwo-dimensionally arranged in an array form.
 32. An image display deviceaccording to claim 29, characterized in that said light source has agroup of R color LEDs, a group of G color LEDs, and a group of B colorLEDs, each being constituted by a plurality of the respective color LEDstwo-dimensionally arranged in an array form, and an RGB light beamdivision multiplexer prism that combines the lights emitted by thosegroups.
 33. An image display device according to claim 29, characterizedin that the optical system, which leads the light emitted from saidlight source to said two-dimensionally light emitting type photoelectricdevices, has an illumination uniformizing optical system.
 34. An imagedisplay device according to claim 33, characterized in that saidillumination uniformizing optical system is at least one rod and in thatthe final exit plane of said rod and the surface of saidtwo-dimensionally light emitting type photoelectric devices are madesubstantially conjugate with each other.
 35. An image display deviceaccording to claim 30, wherein said light source is a plurality of whitelight LEDs two-dimensionally arranged in an array form.
 36. An imagedisplay device according to claim 30, characterized in that said lightsource has a group of R color LEDs, a group of G color LEDs, and a groupof B color LEDs, each being constituted by a plurality of the respectivecolor LEDs two-dimensionally arranged in an array form, and an RGB lightbeam division multiplexer prism that combines the lights emitted bythose groups.
 37. An image display device according to claim 30,characterized in that the optical system, which leads the light emittedfrom said light source to said two-dimensionally light emitting typephotoelectric devices, has an illumination uniformizing optical system.38. An image display device according to claim 37, characterized in thatsaid illumination uniformizing optical system is at least one rod and inthat the final exit plane of said rod and the surface of saidtwo-dimensionally light emitting type photoelectric devices are madesubstantially conjugate with each other.
 39. An image display deviceaccording to claim 2, characterized in that at least one surface of thelens surfaces of said convex lens(es) is a conic surface with conicconstant K<−1.
 40. An image display device according to claim 3,characterized in that at least one surface of the lens surfaces of saidconvex lens(es) is a conic surface with conic constant K<−1.
 41. Animage display device according to claim 4, characterized in that atleast one surface of the lens surfaces of said convex lens(es) is aconic surface with conic constant K<−1.
 42. An image display deviceaccording to claim 7, characterized in that at least one surface of thelens surfaces of said convex lens(es) is a conic surface with conicconstant K<0.
 43. An image display device according to claim 42,characterized in that at least one surface of the lens surfaces of saidconvex lens(es) is a conic surface with conic constant K<−1.